MARYLAND  GEOLOGICAL  SURVEY 


CALVERT  COUNTY 


MARYLAND 


GEOLOGICAL  SURVEY 


CALVERT  COUNTY 


BALTIMORE 

THE  JOHNS  HOPKINS  PRESS 
1907 


JSorb  (gafttmore  (preee 

BALTIMORE,  MD.,  U.  8.  A. 


AT?Y 

UNIVFT>*TTv  rw  CALIFORNIA 
BARBARA 


COMMISSION 


EDWIN"  WARFIELD, PRESIDENT. 

GOVERNOR    OF    MARYLAND. 

GORDON  T.  ATKINSON, 

COMPTROLLER    OF    MARYLAND. 

IRA  REMSEN, EXECUTIVE  OFFICER. 

PRESIDENT   OF   THE   JOHNS    HOPKINS    UNIVERSITY. 

R.  W.  SILVESTER, SECRETARY. 

PRESIDENT   OF   THE   MARYLAND   AGRICULTURAL   COLLEGE. 


SCIENTIFIC  STAFF 

WM.  BULLOCK  CLARK, STATE  GEOLOGIST. 

SUPERINTENDENT  OF  THE  SURVEY. 


EDWARD  B.  MATHEWS,  .        .        .    ASSISTANT  STATE  GEOLOGIST. 

GEORGE  B.  SHATTUCK,     .        .        .        .        .        .        .        GEOLOGIST. 

B.  L.  MILLER,        .        . GEOLOGIST. 

C.  K.  SWARTZ, GEOLOGIST. 

E.  W.  BERRY,  .        . GEOLOGIST. 

A.  BIBBINS, GEOLOGIST. 


Also  with  the  cooperation  of  several  members  of  the  scientific  bureaus 
of  the  National  Government. 


LETTER  OF  TRANSMITTAL 

To  His  Excellency  EDWIN  WARFIELD, 

Governor  of  Maryland  and  President  of  the  Geological  Survey 
Commission. 

Sir: — I  have  the  honor  to  present  herewith  a  report  on  The  Physical 
Features  of  Calvert  County.  This  volume  is  the  fourth  of  a  series  of  re- 
ports on  the  county  resources,  and  is  accompanied  by  large  scale  topo- 
graphical, geological,  and  agricultural  soil  maps.  The  information  con- 
tained in  this  volume  will  prove  of  both  economic  and  educational  value 
to  the  residents  of  Calvert  County  as  well  as  to  those  who  may  desire  in- 
formation regarding  this  section  of  the  State.  I  am, 

Very  respectfully, 

WM.  BULLOCK  CLARK, 

State  Geologist. 
JOHNS  HOPKINS  UNIVERSITY, 
BALTIMORE,  January,  1907. 


CONTENTS 


PAGE 

PREFACE      17 

INTRODUCTION     21 

DEVELOPMENT  OF  KNOWLEDGE  CONCERNING  THE  PHYSICAL 
FEATURES  OF  CALVERT  COUNTY,  WITH  BIBLIOG- 
RAPHY. BY  GEORGE  BUBBANK  SHATTUCK  25 

INTRODUCTORY    25 

HISTORICAL  REVIEW     25 

The  History  of  Geographic  Research 26 

The  History  of  Geologic  Research 31 

BIBLIOGRAPHY 39 

THE  PHYSIOGRAPHY  OF  CALVERT  COUNTY.     BY  GEORGE  BURBANK 

SHATTUCK     55 

INTRODUCTORY    55 

TOPOGRAPHIC  DESCRIPTION   56 

The  Drainage  of  Calvert  County 59 

The  Structure  of  the  Coastal  Plain 61 

TOPOGRAPHIC  HISTORY    61 

The   Sunderland   Stage    62 

The  Wicomico  Stage   63 

The  Talbot  Stage    64 

The  Recent  Stage   65 

THE     GEOLOGY     OF     CALVERT     COUNTY.       BY     GEORGE     BURBANK 

SHATTUCK     67 

INTRODUCTORY     67 

THE  EOCENE   68 

THE  PAMUNKEY  GROUP    68 

The  Nan jemoy  Formation 68 

THE  MIOCENE    70 

THE  CHESAPEAKE  GROUP  70 

The  Calvert  Formation  70 

Areal   Distribution 70 

Strike,  Dip  and  Thickness  72 

Character  of  Materials    73 

Stratigraphic   Relations    73 

Sub-Divisions                                                                                                    .  73 


12  CONTENTS 

PAGE 

Fairhaven  Diatomaceous  Earth   73 

Plum  Point  Marls  75 

The  Choptank  Formation  78 

Areal   Distribution    79 

Strike,  Dip  and  Thickness  79 

Character  of  Materials    80 

Stratigraphic   Relations 81 

Sub-Divisions    81 

The  St.  Mary's  Formation  83 

Areal   Distribution    83 

Strike,  Dip  and  Thickness  84 

Character  of  Materials   84 

Stratigraphic   Relations    84 

Sub-Divisions     85 

Local  Sections 86 

Origin  of  Materials    92 

THE  PLEISTOCENE 93 

THE  COLUMBIA  GROUP 93 

The  Sunderland  Formation  94 

Areal  Distribution  94 

Structure  and  Thickness  95 

Character  of  Materials  96 

Stratigraphic  Relations  96 

Local  Sections  98 

The  Wicomico  Formation  99 

Areal  Distribution  99 

Structure  and  Thickness  100 

Character  of  Materials  100 

Stratigraphic  Relations  101 

Local  Sections  101 

The  Talbot  Formation  101 

Areal  Distribution  . . 102 

Structure  and  Thickness  102 

Character  of  Materials  103 

Stratigraphic  Relations  103 

Local  Sections  104 

Origin  of  Materials    105 

THE  INTERPRETATION  OF  THE  GEOLOGICAL  RECORD 106 

Sedimentary  Record  of  the  Nanjemoy  Formation 106 

Sedimentary  Record  of  the  Chesapeake  Group 106 

Sedimentary  Record  of  the  Columbia  Group 107 

THE  MINERAL  RESOURCES  OF  CALVERT  COUNTY.     BY  BENJAMIN 

L.  MILLER    , 123 

INTRODUCTORY                                                                                                  .  123 


MARYLAND   GEOLOGICAL    SURVEY  13 

PAGE 

THE  NATURAL  DEPOSITS    123 

The   Clays 123 

Tertiary  Clays   124 

Quaternary  Clays    125 

The    Sands    127 

The  Gravels    128 

The  Building  Stone   128 

The  Marls   128 

The  Diatomaceous  Earth   130 

THE  WATEB  RESOURCES   131 

Springs      132 

Dug  Wells   132 

Artesian  Wells  133 

The  Magothy  ( ?)  Horizon   133 

The  Calvert  Horizon 134 

THE  SOILS  OF  CALVERT  COUNTY.     BY  JAY  A.  BONSTEEL  AND  R.  T. 

AVON  BTJBKE 135 

INTRODUCTORY  135 

Physical  Geography  135 

Geology  137 

SOIL  TYPES  141 

The  Norfolk  Loam  141 

The  Leonardtown  Loam  143 

The  Susquehanna  Gravel  147 

The  Windsor  Sand  148 

The  Norfolk  Sand  151 

The  Sassafras  Loam  154 

The  Sassafras  Sandy  Loam  157 

The  Meadow  Land  158 

The  Swamp  Land  160 

THE  AGRICULTURAL  CONDITIONS  161 

THE  CLIMATE  OF  CALVERT  COUNTY.     BY  C.  F.  VON  HERRMANN 169 

INTRODUCTORY     169 

The  Factors  Controlling  Climate   169 

The  Physiographic  Features  of  Calvert  County 171 

The  Influence  of  Water  on  the  Distribution  of  Temperature 173 

METEOROLOGICAL  DATA  AVAILABLE  FOR  CALVERT  COUNTY 177 

TEMPERATURE  CONDITIONS    178 

Precipitation     .  .  181 


14  CONTENTS 

PAGE 

THE  CLIMATOLOGY  OF  SOLOMONS 182 

INTRODUCTORY     182 

TEMPERATURE  CONDITIONS    183 

Means  of  Maximum  and  Minimum  Temperatures 191 

Extremes  of  Temperature:  Duration  of  Warm  Periods 192 

Frequency  and  Duration  of  Cold  Periods 195 

The  Advent  of  Spring 197 

PRECIPITATION 198 

Duration  of  Dry  and  Wet  Periods  201 

Snowfall     203 

WINDS  AND  WEATHER  204 

THE  HYDROGRAPHY  OF  CALVERT  COUNTY.     By  N.  C.  GROVER 207 

Hall   Creek    207 

Lyons  Creek   208 

St.  Leonard  Creek 208 

THE   MAGNETIC   DECLINATION   IN   CALVERT   COUNTY.     By   L.   A. 

BAUER    209 

DESCRIPTION  OF  STATIONS    209 

MERIDIAN  LINE  210 

THE  FORESTS  OF  CALVERT  COUNTY.     By  H.  M.  CURRAN 213 

AREA  OF  COUNTY   213 

WOODLANDS     213 

Slope  Timber    213 

Stream   Bottoms    214 

Old  Fields   215 

Forest  Trees 216 

Wood  Consumption  218 

PAST  TREATMENT  OF  WOODLANDS  218 

FUTURE  IMPROVEMENT 219 

CULTURAL  TREATMENT 221 

INDEX                                                                                                                         ..  223 


ILLUSTRATIONS 


PLATE  FACING   PAGE 

I.     Fig.  1. — View    showing    indurated    layer    near    base    of   Miocene, 

Lyons  Creek   32 

FIG.  2. — View    of    Patuxent    River    showing    works    of   Maryland 

Silicate   Company    32 

II.     Fig.    1. — View   showing   Calvert   formation   at   mouth   of   Parker 

Creek     56 

Fig.    2. — View   showing   fossils   in   Calvert   formation,   11/2    miles 
north  of  Point  of  Rocks 56 

III.  Fig.  1. — View  of  the  Calvert  Cliffs  near  Governor  Run 64 

Fig.  2. — View  showing  the  Choptank  formation  near  the  Mouth 

of  St.  Leonard  Creek  64 

IV.  Characteristic  Fossils  of  the  Miocene  formations  of  Calvert  County.    72 
V.     Fig.  1. — View  showing  St.  Mary's  formation  at  Cove  Point 80 

Fig.    2. — View    showing   the    Sunderland    formation    near    Battle 

Creek     80 

VI.     Characteristic    Fossil    Plants    from    the    Pleistocene    of    Calvert 

County    96 

VII.     Fig.  1. — View  showing  Sunderland  surface  near  Huntingtown. . . .  104 
Fig.  2. — View     showing     Sunderland-Wicomico     scarp,     Wicomico 

surface  in  foreground,  Hunting  Creek  Valley 10 1 

VIII.     Fig.  1. — View    showing    fossil    vegetation    in    Talbot    formation, 

near  Cove  Point   112 

Fig.  2. — View     showing    cross-bedding    in    Wicomico     formation, 

valley  of  Lyons  Creek  112 

IX.     Fig.  1. — View  showing  Talbot  formation  near  Dare's  Wharf 120 

Fig.  2. — View    showing    Wicomico-Talbot    scarp    along    Patuxent 

River  south  of  Cocktown  Creek 120 

X.     Fig.  1. — View     showing    cliffs     of     Diatomaceous     earth,     Lyons 

Wharf     128 

FIG.  2. — View    of   Diatomaceous   earth,    pit   of   Maryland    Silicate 

Company,  Lyons  Wharf 128 

XL     Fig.  1. — View  showing  Cypress  swamp,  Battle  Creek 214 

Fig.  2. — View  showing  Slope  Timber  214 

Views  showing  Second-growth  Cypress  in  Stream  bottoms 216 

Fig.  1. — View  showing  Scrub  Pine  seeding  eroded  slopes 218 

Fig.  2. — View  showing  Scrub  Pine  seeding  eroded  slopes 218 

Fig.  1. — View  showing  development  of  the  White  Oak  as  a  Shade 

Tree     220 

Fig.  2. — View  showing  Scrub  Pine  for  Cordwood 220 


16  ILLUSTRATIONS 

FIGURE  PAGE 

1.  Diagram  showing  Ideal  Arrangement  of  the  Various  Terrace  Forma- 

tions in  the  Maryland  Coastal  Plain 93 

2.  Diagram  showing  approximate   position   of  shore-line   of  Wicomico 

Sea     110 

3.  Diagram  showing  approximate  position  of  shore-line  of  Talbot  Sea. .   Ill 

4.  Diagram  showing  pre-Talbot  valley  115 

5.  Diagram  showing  advancing  Talbot  shore-line  and  ponded  stream..   116 

6.  Diagram  showing  later  stage  in  advance  of  Talbot  shore-line 117 

7.  Ideal  section  showing  advance  of  Talbot  shore-line 118 

8.  Annual  mean  Temperature  curves  189 

9.  Maximum  Temperatures  during  August,  1900 194 

10.  Minimum  Temperatures  during  February,  1899 196 

11.  Precipitation  for  each  month  in  the  year  at  Solomons 200 


PREFACE 

This  volume  is  the  fourth  of  a  series  of  reports  dealing  with  the  physi- 
cal features  of  the  several  counties  of  Maryland. 

The  Introduction  contains  a  brief  statement  regarding  the  location 
and  boundaries  of  Calvert  County  together  with  its  chief  physical  char- 
acteristics. 

The  Physiography  of  Calvert  County,  by  George  B.  Shattuck,  com- 
prises a  discussion  of  the  surface  characteristics  of  the  county,  together 
with  a  description  both  of  the  topographic  forms  and  of  the  agencies 
which  have  produced  them.  A  fuller  discussion  of  this  subject  has  been 
presented  by  Dr.  Shattuck  in  his  report  on  the  Pliocene  and  Pleistocene 
deposits  of  Maryland. 

The  Geology  of  Calvert  County,  by  George  B.  Shattuck,  deals  with 
the  stratigraphy  and  structure  of  the  county.  An  historical  sketch  is 
given  of  the  work  done  by  others  in  this  field  to  which  is  appended  a 
complete  bibliography.  Many  stratigraphical  details  are  presented,  ac- 
companied by  local  sections. 

The  Mineral  Resources  of  Calvert  County,  by  Benjamin  L.  Miller, 
deals  with  the  economic  possibilities  of  the  various  geological  deposits 
of  the  county.  Those  which  have  been  hitherto  employed  are  fully  dis- 
cussed, and  suggestions  are  made  regarding  the  employment  of  others 
not  yet  utilized. 

The  Soils  of  Calvert  County,  by  Jay  A.  Bonsteel  and  K.  T.  Avon 
Burke,  contains  a  discussion  of  the  leading  soil  types  of  the  county  and 
their  relation  to  the  several  geological  formations.  This  investigation 
was  conducted  under  the  direct  supervision  of  Professor  Milton  Whit- 
ney, Director  of  the  Bureau  of  Soils  of  the  U.  S.  Department  of  Agri- 
culture. 

The  Climate  of  Calvert  County,  by  C.  F.  von  Herrmann,  is  an  impor- 
tant contribution  to  the  study  of  the  climatic  features  of  the  county. 


18  PREFACE 

Mr.  von  Herrmann  is  Section  Director  in  Baltimore  of  the  U.  S.  Weather 
Bureau  and  is  also  Meteorologist  of  the  Maryland  State  Weather 
Service. 

The  Hydrography  of  Calvert  County,  by  N.  C.  Grover,  gives  a  brief 
account  of  the  water  supply  of  the  county  which,  as  in  the  case  of  the 
other  Coastal  Plain  counties,  affords  but  little  power  for  commercial  pur- 
poses. The  author  of  this  chapter  is  a  member  of  the  Hydrographic  Di- 
vision of  the  U.  S.  Geological  Survey. 

The  Magnetic  Declination  in  Calvert  County,  by  L.  A.  Bauer,  con- 
tains much  important  information  for  the  local  surveyors  of  the  county. 
Dr.  Bauer  has  been  in  charge  of  the  magnetic  investigations  since  the 
organization  of  the  Survey  and  has  already  published  two  important 
general  reports  upon  this  subject.  He  is  the  Director  of  the  Depart- 
ment of  International  Eesearch  in  Terrestrial  Magnetism  of  the  Car- 
negie Institution. 

The  Forests  of  Calvert  County,  by  H.  M.  Curran,  is  an  important  con- 
tribution and  should  prove  of  value  in  the  further  development  of  the 
forestry  interests  of  the  county.  Mr.  Curran  is  a  member  of  the  U.  S. 
Forest  Service. 

The  State  Geological  Survey  desires  to  extend  its  thanks  to  the  several 
National  organizations  which  have  liberally  aided  it  in  the  preparation 
of  several  of  the  papers  contained  in  this  volume.  The  Director  of  the 
U.  S.  Geological  Survey,  the  Chief  of  the  U.  S.  Weather  Bureau,  the 
Chief  of  the  IT.  S.  Forest  Service  and  the  Chief  of  the  Bureau  of  Soils 
of  the  U.  S.  Department  of  Agriculture  have  granted  many  facilities  for 
the  conduct  of  the  several  investigations  and  the  value  of  the  report  has 
been  much  enhanced  thereby. 


THE 


PHYSICAL  FEATURES 


OF 


CALVERT  COUNTY 


THE  PHYSICAL  FEATURES  OF 
CALVERT  COUNTY 


INTRODUCTION 

Calvert  County  constitutes  with  Anne  Arundel,  Prince  George's, 
Charles,  and  St.  Mary's  counties,  what  is  called  Southern  Maryland.  It 
is  located  between  the  parallels  38°  19'  and  38°  46'  north  latitude  and 
the  meridians  76°  23'  and  76°  42'  west  longitude  and  covers  an  area  of 
216.8  square  miles.  Calvert  County  was  first  established  in  1654,  its 
confines  at  that  time  embracing  portions  of  what  are  now  Anne  Arundel 
and  Prince  George's  counties,  although  its  westernmost  limits  were 
somewhat  indefinite.  In  1674  its  northern  boundary  was  restricted, 
although  still  comprising  a  small  area  in  the  northeastern  part  of  the 
county  which  in  1823  was  incorporated  with  Anne  Arundel  County, 
the  present  limits  of  Calvert  County  dating  from  that  time. 

Calvert  County  is  entirely  surrounded  by  navigable  waters  except  along 
its  northern  boundary  adjacent  to  Anne  Arundel  County.  The  eastern 
boundary  of  the  county  is  the  Chesapeake  Bay,  while  its  southern  and 
western  boundaries  are  marked  by  the  waters  of  the  Patuxent  Eiver. 

Calvert  County  constitutes  a  peninsula  along  which  from  north  to  south 
runs  an  elevated  plain  that  gradually  descends  from  an  extreme  eleva- 
tion of  somewhat  over  180  feet  near  the  northern  limits  of  the  county 
to  about  100  feet  in  the  south.  From  this  highland,  the  watershed  of 
which  is  not  far  from  the  Chesapeake  Bay,  the  drainage  is  to  the  east- 
ward by  short  courses  to  the  Chesapeake  Bay  and  to  the  westward  by 
longer  channels  to  the  Patuxent  River.  The  county-town  is  Prince 
Frederick,  situated  on  the  upland  plain  near  the  center  of  the  county. 


22  INTRODUCTION 

The  largest  settlement  in  the  County  is  Solomons,  located  on  Solomons 
Island  near  the  mouth  of  the  Patuxent  River.  Its  citizens  are  largely 
engaged  in  the  oyster  trade. 

Calvert  County  is  essentially  an  agricultural  region,  although  its  prox- 
imity to  the  waters  of  the  Chesapeake  Bay  and  the  Patuxent  River  gives 
it  an  advantageous  position  in  the  oyster  industry,  many  of  its  citizens 
being  engaged  in  that  business,  which  has  meant  so  much  to  the  material 
prosperity  of  the  State. 

The  soils  of  the  county  are  well  adapted  to  the  growth  of  tobacco, 
corn,  wheat  and  rye,  while  small  fruits,  especially  peaches,  can  be  suc- 
cessfully raised.  Still  other  areas  are  well  adapted  to  the  raising  of  sheep 
and  cattle.  The  lumbering  interests  of  the  county  have  been  of  consid- 
erable importance  in  the  past  and  with  the  introduction  of  modern 
methods  of  forest  management  may  again  be  revived,  as  there  are  many 
large  tracts  in  the  county  where  valuable  wood-lands  could  be  advan- 
tageously developed. 

The  mineral  resources  of  the  county  are  not  important,  although  the 
beds  of  diatomaceous  earth  on  Lyons  Creek  have  been  extensively  worked 
at  different  times  and  afford  a.  high  grade  silica  which  is  commonly 
known  in  the  trade  as  tripoli.  These  silica  deposits  underlie  a  consider- 
able area  in  the  extreme  northern  part  of  the  county.  There  are  also 
beds  of  shell  marl  and  clay,  but  they  have  not  as  yet  been  employed  to 
any  great  extent  for  economic  purposes. 

The  transportation  facilities  of  Calvert  County  are  mainly  furnished 
by  the  Baltimore,  Chesapeake  and  Atlantic  Railroad  which  runs  frequent 
boats  to  various  landings  on  the  Bay  and  river  shores,  the  so-called  river 
being  in  reality  a  tidal  estuary  which  with  the  Chesapeake  Bay  occupies 
through  recent  subsidence  of  the  country,  the  channels  of  earlier  streams. 
Only  within  the  last  decade  has  the  railroad  penetrated  into  the  confines 
of  the  county,  when  the  Chesapeake  Beach  Railroad  was  built,  to  develop 
a  resort  on  the  shores  of  the  Chesapeake  Bay.  Many  attempts  have  been 
made  to  construct  a  railroad  across  the  county  from  north  to  south  with 


MARYLAND    GEOLOGICAL    SUIVKY  23 

its  terminus  at  Drum  Point,  and  this  plan  seems  now  on  the  point  of 
realization.  With  the  completion  of  this  line  few  counties  in  the  State 
will  enjoy  such  exceptional  transportation  facilities,  as  no  place  in  the 
county  would  then  be  more  than  a  few  miles  from  a  shipping  point. 

The  present  volume  contains  a  discussion  of  the  physiography,  geology, 
agricultural  soils,  hydrography,  climate,  terrestrial  magnetism  and  for- 
estry of  the  county,  which  together  constitute  the  physical  features.  All 
of  these  are  essential  to  an  understanding  of  the  natural  resources  and 
possess  an  interest  not  only  from  an  economic  but  from  an  educational 
view-point.  W.  B.  C. 


DEVELOPMENT  OF  KNOWLEDGE  CONCERN- 
ING  THE  PHYSICAL  FEATURES  OF 
CALVERT  COUNTY,  WITH 
BIBLIOGRAPHY 

BY 

GEORGE  BURBANK  SHATTUCK 


INTRODUCTORY. 

The  miscellaneous  observations  made  by  the  early  explorers  of  Calvert 
County  pertained  to  subjects  which  have  now  become  distinct  fields  of 
investigation.  Notes  which  relate  to  discoveries  in  geography  and 
geology  have  been  gathered  from  various  sources  by  the  author  who  has 
grouped  together  the  most  important  of  them  under  their  respective 
heads.  The  review  of  geographical  research  begins  with  a  summary  of 
the  exploration  made  by  Capt.  John  Smith  in  1608  and  ends  with  the 
recent  work  of  the  State  Geological  Survey  during  the  summer  of  1902. 
The  account  of  the  geological  research  begins  with  Wm.  Maclure's  investi- 
gations in  1809  and  ends  with  the  latest  publications  made  in  1906. 

HISTORICAL  EEVIEW. 

Calvert  County,  which  occupies  a  narrow  neck  of  land  between  Chesa- 
peake Bay  on  the  east  and  the  deep  estuary  of  the  Patuxent  Kiver  on  the 
south  and  west,  is  favorably  situated  for  exploration  and  colonization 
and  was  consequently  visited  and  settled  by  the  Europeans  at  a  very 
early  date.  As  is  customary  in  a  new  country,  explorations  were  at  first 
incomplete  and  the  maps  made  by  the  early  geographers  far  from  cor- 
rect. But  as  time  advanced  and  the  country  became  more  thoroughly 
explored,  the  rough  preliminary  maps  were  replaced  by  more  exact  and 
satisfactory  ones.  The  history  of  exploration  in  Calvert  County  is, 
therefore,  a  narrative  of  the  gradual  accumulation  of  information  which 
at  first  was  vague  and  general,  but  now  has  become  definite  and  specific. 
3 


20  THE   PHYSICAL   FEATURES   OF    CALVERT    COUNTY 

THE  HISTORY  OF  GEOGRAPHIC   RESEARCH. 

The  first  geographic  exploration1  in  the  region  which  is  now  known 
as  Calvert  County  was  carried  on  by  Captain  John  Smith  and  a  few  com- 
panions in  the  summer  of  1608,  although  the  results  were  not  pub- 
lished until  1612-14.  The  motive  which  prompted  Smith  to  this  under- 
taking was  the  exploration  of  Chesapeake  Bay  and  the  adjacent  country, 
so  that  the  examination  of  Calvert  County  was  only  a  portion  of  the 
work  accomplished.  His  description  of  the  country  along  the  Calvert 
Cliffs  is  as  follows : 

"  But  finding  this  Easterne  shore,  shallow  broken  Isles,  and  for  the 
most  part  without  fresh  water,  we  passed  by  the  straits  of  Limbo 
[Hooper  or  Kedge  Straits.]  for  the  Westerne  shore;  so  broad  is  the 
bay  here,  we  could  scarce  perceiue  the  great  high  clifts  on  the  other  side : 
by  them  we  Anchored  that  night  and  called  them  Riccards  CKftes  [Cal- 
vert Cliffs].  30  leagues  we  sayled  more  Northwards  not  finding  any 
inhabitants,  leaving  all  the  Eastern  shore,  lowe  Islandes,  but  ouergrowne 
with  wood,  as  all  the  Coast  beyond  them  so  farre  as  wee  could  see;  the 
Westerne  shore  by  which  we  sayled  we  found  all  along  well  watered,  but 
very  mountanous  and  barren,  the  vallies  very  fertill,  but  extreame  thicke 
of  small  wood  so  well  as  trees,  and  much  frequented  with  wolues,  Beares, 
Deere,  and  other  wild  beasts.  We  passed  many  shallow  creekes,  but  the 
first  we  found  Navigable  for  a  ship,  we  called  Bolus  [Patapsco]." 

Smith  did  not  spend  in  all  much  more  than  a  month  in  his  exploration 
of  Chesapeake  Bay,  but  in  this  short  time  gathered  material  which  was 
afterward  presented  in  a  remarkably  well  proportioned  map,  if  one  con- 
siders the  difficulties  which  he  encountered  and  the  extremely  rough 
methods  of  surveying  which  he  employed.  This  map  remained  for  a 
long  time  unsurpassed  and  served  as  a  basis  of  exploration  and  settle- 
ment. In  examining  the  map  which  Smith  compiled  from  notes  taken 
on  this  famous  voyage  of  discovery,  one  is  struck  with  the  accuracy  with 
which  the  main  features  of  Calvert  County  are  recorded.  The  straight 

1  For  illustrations  of  these  early  maps  and  the  conditions  under  which 
they  were  made,  see  Mathews,  Maps  and  Mapmakers  of  Maryland,  Md.  Geol. 
Survey,  vol.  ii,  1898,  pp.  377-488. 


.MARYLAND   GEOLOGICAL    SURVEY  27 

shore  line  of  Chesapeake  Bay  along  the  Rickards  Cliff es  (Calvert  Cliffs) 
is  characteristic,  but  the  cliffs  themselves  are  represented  by  conventional 
hillocks  which  are  employed  consistently  in  other  portions  of  the  map 
to  represent  areas  of  elevation.  The  Patuxent  Eiver  is  also  defined  with 
surprising  accuracy  and  the  surface  of  the  county  is  dotted  over  with 
names  of  Indian  settlements  and  with  trees  of  various  kinds  which  were 
probably  meant  to  indicate  different  types  of  forest  growth. 

In  1635  the  Lord  Baltimore  map  appeared.  This  map  included  most  of 
tidewater  Maryland,  but  when  compared  with  the  Smith  map  of  the  same 
region,  is  far  less  accurate  in  detail  and  very  much  more  crude  in  execu- 
tion. Calvert  County  is  well  defined  and  in  outlines  does  not  differ 
markedly  from  the  same  region  represented  by  Smith.  A  hillock  shows 
roughly  the  position  of  the  Calvert  Cliffs  and  the  same  methods  which 
were  used  by  Smith  are  employed  to  represent  forests. 

In  1651,  the  Farrer  map  of  the  environs  of  Chesapeake  Bay  and  the 
surrounding  country  was  published.  This  map,  which  was  drawn  by 
Virginia  Farrer,  was  distorted  so  as  to  prove  that  "  in  ten  dayes  march 
with  50  foote  and  30  horsemen  from  the  head  of  leames  Eiver,  ouer 
those  hills  and  through  the  rich  adiacent  Vallyes  beautified  with  proffit- 
able  river  which  necessarily  must  run  into  yt  peacefull  Indian  Sea  "  one 
might  arrive  in  New  Albion  or  California.  In  this  map,  the  region  now 
occupied  by  Calvert  County  was  so  distorted  that  the  map  was  practically 
useless. 

Fiften  years  later,  in  1666,  George  Alsop  published  a  map  which  em- 
braced the  environs  of  Chesapeake  Bay  from  a  point  in  Virginia  a  little 
south  of  the  Potomac  Eiver  northward  to  what  is  now  in  part  Delaware 
and  Pennsylvania.  The  map  was  issued  in  a  small  pamphlet  and  was 
based  on  personal  observation  throughout  the  region  represented.  Al- 
though many  of  the  details  which  were  placed  on  the  map  had  been 
obtained  by  personal  exploration,  still  Alsop  was  doubtless  familiar  with 
the  early  Smith  map  and  was  guided  not  a  little  by  it.  The  map  is  on 
a  larger  scale  and  shows  more  detail  than  represented  by  Smith,  yet  it 
adds  little  to  the  real  knowledge  of  the  region,  because  of  its  diagram- 
matic character  and  extremely  distorted  proportions.  It  is  just  such  a 


28  THE   PHYSICAL   FEATURES   OF    CALVERT    COUNTY 

map  as  might  be  produced  by  a  rover  or  an  untrained  hunter  who  had 
explored  the  region  in  a  general  way.  The  representation  of  the  Pa- 
tuxent  Kiver  is  extremely  diagrammatic  and  conventional.  Near  its  head 
waters,  there  is  a  sketch  of  an  animal  which  is  probably  meant  to  indi- 
cate a  fox,  as  its  tail  is  represented  as  somewhat  bushy.  The  shore  of 
Chesapeake  Bay  occupied  by  the  Calvert  Cliffs  is  not  as  accurately  rep- 
resented as  the  same  region  in  the  Smith  and  Lord  Baltimore  maps,  for 
in  place  of  being  straight  and  devoid  of  inlets,  Alsop  has  indicated  it  as 
quite  irregular.  The  surface  of  the  region  occupied  by  Calvert  County 
is  depicted  as  irregular  and  hilly  and  the  elevations,  in  place  of  being 
clustered  along  the  shore  line  in  the  region  of  the  Calvert  Cliffs,  as  was 
done  in  earlier  maps,  are  here  scattered  over  the  entire  surface  of  the 
county.  The  convention  is  probably  meant  to  indicate  the  irregular  sur- 
face of  the  region,  a  conception  which  a  hunter  travelling  over  the 
country  might  easily  gain  as  he  worked  his  way  up  the  stream  valleys  and 
across  the  narrow  but  flat-top  divides.  In  addition  to  the  features  just 
mentioned,  a  drawing  of  a  house  indicates  possibly  a  settlement,  while 
one  or  two  trees  are  added  to  suggest  the  presence  of  forests. 

The  map  which  Smith  published  in  1612  was  not  excelled  by 
other  explorers  until  1670,  when  Augustin  Herrman  brought  out  a  map 
of  the  region  extending  from  southern  New  Jersey  to  southern  Virginia. 
Herrman,  it  seems,  offered  to  make  a  map  of  Lord  Baltimore's  territory 
provided  Lord  Baltimore  in  return  would  grant  him  a  manor  along  Bo- 
hemia Eiver;  this  proposition  was  accepted  in  1660  and  Herrman  soon 
after  began  to  fulfil  his  part  of  the  contract.  He  was  engaged  in  this 
work  for  about  ten  years,  and  the  map  which  he  finally  produced  indi- 
cates that  he  had  considerable  talent,  not  only  as  a  surveyor,  but  also  as 
a  draughtsman.  The  cartographic  work  of  Calvert  County  was  the 
best  which  had  appeared  up  to  that  time.  The  name  "Calvert 
County "  here  appears  on  the  map  together  with  a  number 
of  the  more  important  settlements  scattered  over  the  area.  The  coast 
line  bordering  the  Bay  is  represented,  not  straight  as  in  some  of  the 
previous  maps,  but  curved,  approximating  the  outline  as  it  actually 
exists,  although  the  embayment  is  somewhat  deeper  than  it  should  be. 


MARYLAND   GEOLOGICAL    SURVEY  29 

The  precipitous  character  of  this  coast  had  by  this  time  probably  become 
a  well-known  landmark  to  mariners,  for  Herrman  has  placed  the  ex- 
pression "  The  Cliffs "  opposite  the  famous  Calvert  Cliffs  to  indicate 
their  presence.  The  Patuxent  Kiver  is  mapped  more  accurately  than  in 
any  of  the  previous  maps,  not  excepting  the  Smith  map,  and  is  far 
superior  to  the  cartographic  work  on  either  the  Farrer  or  the  Lord  Balti- 
more maps. 

The  next  general  map  of  the  Chesapeake  shore  to  appear  was  published 
by  Walter  Hoxton  in  1735.  Hoxton  was  a  captain  in  the  Merchant 
Marine  service  between  London  and  Virginia.  In  regard  to  his  own  map, 
he  says : 

"  In  this  Draught  all  the  Principal  Points,  and  all  the  Shoals  and 
Soundings  are  Exactly  Laid  Down,  but  as  I  have  not  had  Opportunity  to 
Survey  all  of  ye  Bays,  Eivers  and  Creeks,  I  have  distinguisht  what  is  my 
own  doing  by  a  Shading  within  the  Line,  from  the  outer  part  of  the 
Coast  which  to  make  this  Map  as  complete  as  at  present  I  am  able,  have 
borrow'd  from  the  Old  Map,  &  are  Traced  by  a  Single  Line  without 
Shading.  1ST.  B.  The  Depths  of  Water  are  set  down  in  Fathoms  as 
farr  up  as  Spes  Utie  Island,  but  above  that  in  Feet."  The  particular 
point  which  is  of  interest  in  regard  to  this  chart  is  the  mapping  of  the 
shore  line  from  Point  Lookout  northward  to  North  East  in  Cecil  County, 
and  the  indication  of  various  depths  of  water  in  the  Bay  by  means  of 
figures  placed  over  the  spot  where  they  occur,  after  the  manner  still  em- 
ployed by  the  United  States  Coast  and  Geodetic  Survey. 

In  1776,  at  about  the  time  of  the  outbreak  of  the  Revolutionary  War, 
Anthony  Smith  published  a  chart  of  Chesapeake  Bay  on  a  scale  of  3£ 
miles  to  the  inch.  This  chart  was  intended  for  a  guide  to  navigators, 
and  such  information  as  shoals,  channels,  islands,  and  the  various  depths 
of  water  were  represented. 

After  the  close  of  the  war,  in  1794,  Dennis  Griffith  assembled  all 
available  information  and  published  a  map  of  the  entire  State  which  was 
not  excelled  until  Alexander  began  the  publication  of  his  maps  in  the 
fourth  decade  of  the  last  century.  In  this  map,  the  shape  of  Calvert 
County  was  quite  accurately  portrayed  and  the  configuration  of  the  Bay 


30  THE   PHYSICAL    FEATURES   OF    CALVEKT    COUNTY 

shore  was  an  improvement  on  that  of  Herrman,  but  the  shore  line  of  the 
Patuxent  Kiver  was  considerably  generalized.  There  was  additional  in- 
formation regarding  the  small  streams  which  drain  the  surface  of  the 
region  and  many  of  the  localities  which  occur  on  the  most  recent  maps 
were  indicated. 

A  marked  advance  in  the  cartography  of  this  region  occurred  in  1836, 
when  Prof.  J.  T.  Ducatel,  then  State  Geologist  of  Maryland,  published 
his  geological  report  of  Calvert  County.  This  report  was  accompanied 
by  a  map  of  the  region  prepared  by  John  H.  Alexander.  This  map  of 
Calvert  County  was  the  best  that  had  been  produced  and  was  not  ex- 
celled until  the  present  Geological  Survey  published  the  Calvert  County 
map.  In  the  Alexander  map,  the  topography  was  expressed  by  hachure 
and  the  map  executed  on  the  scale  of  1 :  150,000.  The  prominent  points 
along  the  Bay  shore  and  the  Patuxent  Eiver  were  mapped  and  named,  and 
the  little  streams  which  drain  the  interior  of  Calvert  County  were  indi- 
cated. A  new  feature  in  the  map  was  here  introduced  in  the 
mapping  of  roads,  of  which  the  principal  ones  were  shown.  Prominent 
points  in  the  topography,  such  as  Hollin  Cliff,  Flag  Pond,  Drum  Point, 
etc.,  were  indicated. 

During  the  summer  of  1845,  the  United  States  Coast  and  Geodetic 
Survey  began  a  detailed  survey  of  Chesapeake  Bay.  Work  was  com- 
menced first  about  Havre  de  Grace  and  the  head  of  the  Bay  and  by  1851 
had  reached  as  far  south  as  Point  Lookout.  The  Potomac  and  Patuxent 
rivers  were  last  to  receive  attention  and  the  latter  was  not  mapped  until 
1860. 

The  maps,  which  were  subsequently  published,  attained  a  very  high 
grade  of  workmanship.  Besides  the  position  of  the  shore  line,  they  in- 
dicated by  means  of  numerals,  the  depths  of  water  in  feet  and  fathoms, 
the  character  of  the  bottom  and  the  topography  of  the  coast  for  about 
two  miles  back  from  the  shore  line. 

With  the  exception  of  the  State  map  published  by  Martenet  in  1865, 
which  has  been  revised  from  time  to  time,  no  other  map  work  of  im- 
portance was  undertaken  until  1890,  when  the  United  States  Geological 
Survey  began  systematic  topographic  work  in  southern  Maryland.  In 


MARYLAND   GEOLOGICAL    SURVEY  31 

that  year,  the  coast  line  and  the  interior  of  Calvert  County  were  surveyed 
and  subsequently  published  in  four  sheets.  Each  one  of  these  sheets, 
however,  included  portions  of  territory  lying  outside  of  Calvert  County. 
These  four  sheets  are,  beginning  with  the  northern,  Owensville,  Prince 
Frederick,  Leonardtown,  and  Drum  Point.  The  cartographic  work  of 
the  United  States  Geological  Survey  was  in  advance  of  any  which  had 
been  previously  attempted  in  Calvert  County.  The  quality  of  the  work  was 
no  better  than  that  published  by  the  United  States  Coast  and  Geodetic 
Survey,  but  while  the  former  confined  its  efforts  mostly  to  the  water- 
ways and  mapped  the  adjacent  land  only  a  mile  or  two  from  the  coast, 
the  United  States  Geological  Survey  mapped  the  entire  land  area.  The 
map  was  printed  in  three  colors,  blue,  brown,  and  black.  The  hydrography 
was  represented  in  blue  and  went  into  great  details,  including  not  only 
the  larger  water-ways,  but  also  the  smaller  streams  and  their  minute 
branches.  Belief  was  represented  by  contours  with  a  20-foot  interval 
and  printed  in  brown;  while  the  culture,  including  highways,  bridges, 
railroads,  houses,  and  the  names  of  important  localities,  was  printed  in 
black. 

The  present  Maryland  Geological  Survey,  in  co-operation  with  the 
United  States  Geological  Survey,  revised  this  map  in  the  year  1900,  and 
it  is  on  this  base  that  the  geologic  formations  of  the  county  have  been 
mapped. 

THE  HISTORY  OP  GEOLOGIC   RESEARCH.2 

From  an  early  date  the  attention  of  geologists  has  been  attracted  to 
Calvert  County.  The  reason  for  the  great  interest  in  this  region  is 
probably  due  not  only  to  the  extensive  deposits  of  fossil  beds  which  are 
found  within  its  borders,  but  also  to  the  fine  and  continuous  exposure 
which  is  found  in  the  Calvert  Cliffs  along  the  entire  eastern  margin  of 
the  county,  as  well  as  in  numerous  places  on  the  western  side  along 

2  Many  of  the  broad  generalizations  of  the  early  investigators  in  southern 
Maryland  apply  to  the  entire  region  although  specific  localities  are  seldom 
mentioned.  In  preparing  this  historical  sketch,  it  has  been  necessary  to 
refer  to  these  papers  although  few  of  them  mention  the  name  of  Calvert 
County. 


32          THE  PHYSICAL  FEATURES  OF  CALVERT  COUNTY 

the  Patuxent  Eiver.  The  observations  which  were  made  led  to  con- 
clusions which,  in  the  early  days  of  geologic  research,  were  vague  and 
oftentimes  erroneous;  but  as  time  advanced  and  the  principles 
underlying  geologic  history  have  become  better  understood,  the  papers 
which  have  been  contributed  on  the  region  have  become  more  satisfactory 
and  the  work  more  explicit  and  meritorious.  As  in  the  geographic  re- 
search, so  in  the  geologic,  the  evolution  has  been  from  the  vague  and 
general  to  the  detailed  and  specific. 

The  first  paper  of  importance  was  published  by  William  Maclure  in 
1809.  Although  this  contribution  dealt  in  a  broad  way  with  the  geology 
of  the  United  States,  yet  it  shed  considerable  light  on  Calvert  County. 
He  included  the  entire  Coastal  Plain  of  Maryland  in  one  formation,  the 
"  Alluvial,"  and  so  represented  it  on  a  geologic  map.  He  also  described 
the  unconsolidated  Coastal  Plain  deposits  from  Long  Island  southward, 
indicated  the  boundaries  of  the  Alluvial  formation  and  noted  the  pres- 
ence of  fossils.  This  paper  was  reprinted  in  substance  in  various  maga- 
zines in  1811,  1817,  1818,  and  1826.  Maclure's  views  seem  to  have 
attracted  considerable  attention  at  first,  for  in  1820  Hayden  incorpo- 
rated them  in  his  "  Geological  Essays  "  and  attempted  to  establish  the 
theory  that  the  Alluvial  was  deposited  by  a  great  flood  which  came  down 
from  the  north  and  crossed  North  America  from  northeast  to  southwest. 
The  following  year  Thomas  Nuttall  referred  the  Coastal  Plain  deposits 
to  the  Second  Calcareous  formation  of  Europe,  pointed  out  the  fact  that 
it  occupied  the  country  east  of  the  primitive  and  transition  formations 
of  the  Piedmont  Plateau,  and  fixed  Annapolis  as  about  its  northern  limit. 

Professor  John  Finch,  an  Englishman,  who  was  travelling  in  America 
at  about  this  time,  visited  the  Coastal  Plain  of  Maryland  and  was  so 
impressed  with  its  interesting  geology  and  vast  deposits  of  fossils,  that, 
on  his  return  to  Europe,  he  published  an  account  of  his  experiences  in 
southern  Maryland,  and  drew  some  interesting  conclusions  regarding  its 
geology.  Previously,  in  an  article  which  appeared  in  1824,  he  took  ex- 
ception to  the  classifications  proposed  by  his  predecessors.  He  believed 
that  the  deposits  included  under  the  term  "  Alluvial "  were  contempora- 
neous with  the  Lower  Secondary  and  Tertiary  of  Europe,  Iceland,  Egypt, 


MARYLAND  GEOLOGICAL  SURVEY. 


CALVERT  COUNTY,  PLATE  I. 


FlG    I. — VIEW    SHOWING    INDURATED   LAYER    NEAR   BASE   OF    MIOCENE,    LYONS   CREEK. 


FlG.   2. — VIEW   OF   PATUXENT  RIVER   SHOWING   WORKS   OF   MARYLAND   SILICATE   COMPANY. 


.MARYLAND   GEOLOGICAL    SURVEY  33 

and  Hindoostan.  He  went  farther  and  divided  Maclure's  "  Alluvial " 
up  into  Ferruginous  Sand  and  Plastic  Clay.  He  believed  that  the  Plastic 
Clay  was  Tertiary,  and  based  his  conclusions  on  the  presence  of  amber, 
which  he  found  at  Cape  Sable,  correlating  it  with  the  amber 
of  the  Baltic.  He  also  assigned  to  the  Plastic  Clay  certain  of  the 
Indian  kitchen-middens,  which  are  found  along  the  shore  of  Chesapeake 
Bay,  thus  opening  a  controversy  regarding  the  age  of  these  interesting 
deposits  of  oyster  shells  which  did  not  reach  a  final  settlement  until 
many  years  later.  He  believed  that  the  materials  composing  his  Ferru- 
ginous Sand  and  Plastic  Clay  were  deposited  by  a  flood  from  the  north 
or  the  northwest,  agreeing  somewhat  closely  with  Hayden  in  this  particu- 
lar. His  correlations  were  based  almost  entirely  on  lithologic  distinc- 
tions, supported  by  a  general  similarity  of  fossil  forms.  No  critical 
study  of  the  fossils  was  undertaken,  however,  and  few  localities  were 
given  and  no  geologic  boundaries  whatever.  It  is  consequently  impos- 
sible to  ascertain  where  he  intended  to  place  the  formations  which  we 
now  ascribe  to  the  Eocene,  Miocene,  and  Pleistocene  periods.  One  thing, 
however,  he  perceived  very  keenly — that  the  deposits  in  southern  Mary- 
land would  with  future  work  be  separated  into  many  distinct  formations. 
This  prophecy  has  since  been  fulfilled.  During  the  same  year  Thomas 
Say  described  the  collection  of  fossil  shells  made  by  Finch,  and  among 
them  appeared  many  forms  from  Calvert  County.  This  collection  is 
still  preserved  in  the  British  Museum. 

In  the  year  1825  J.  Van  Eenssellaer  assigned  the  deposits  of  the  Coastal 
Plain  to  the  Tertiary,  and  divided  them  into  Plastic  Clay,  London  Clay, 
and  Upper  Marine.  He  further  correlated  the  deposits  of  Maryland 
which  we  now  know  as  Miocene  with  the  Upper  Marine  of  Europe  and 
probably  in  part  with  the  London  Clay.  It  should  be  noted  here,  how- 
ever, that  Finch  had  previously  used  Upper  Marine  in  a  different  sense. 
He  had  applied  it  to  the  sand  dune  formations  of  Cape  Henry  and 
Staten  Island,  while  Van  Eenssellaer  adopted  it  for  a  true  fossiliferous 
formation  of  very  much  greater  age  than  the  deposits  which  Finch  had 
embraced  under  the  same  name.  Three  years  later,  in  1828,  Morton, 
although  accepting  Van  Renssellaer's  correlation  of  the  great  deposits  of 


34  THE   PHYSICAL    FEATURES   OF    CALVERT    COUNTY 

fossil  shells  in  the  Maryland  Coastal  Plain  with  the  Upper  Marine  of 
Europe,  apparently  used  the  term  in  a  much  wider  sense  than  its  author 
had  employed.  He  also  gave  a  list  of  the  fossil  forms  occurring  in  the 
Upper  Marine,  and  included  some  which  have  since  been  shown  to  be 
later  than  Miocene.  During  the  same  year  Vanuxem  divided  the  Allu- 
vial and  Tertiary  of  the  Atlantic  Coast  into  Secondary,  Tertiary,  and 
Ancient  and  Modern  Alluvial.  In  this  classification  the  Miocene  of 
southern  Maryland  was  included  in  a  part  of  the  Tertiary.  He  stated 
further  that  vast  numbers  of  "  Littoral "  shells  occurred  in  the  Tertiary 
analogous  to  those  of  the  Tertiary  of  the  Paris  and  English  basins. 

Conrad  brought  out  his  first  publications  bearing  on  the  Miocene 
geology  of  Maryland  in  1830.  He  agreed  with  Vanuxem  in  placing 
southern  Maryland  in  the  Tertiary  and  pointed  out  a  number  of  locali- 
ties where  fossil  shells  were  found.  Two  years  later  Conrad  published 
another  paper  in  which  he  divided  up  the  Coastal  Plain  deposits  into  six 
formations.  This  was  the  first  time  that  the  Coastal  Plain  had  been 
classified  so  as  to  show  its  extreme  complexity,  and  from  this  time  on 
it  has  been  dealt  with,  not  as  a  deposit  containing  a  few  formations  but 
as  a  series  of  deposits  complex  in  composition  and  age.  Conrad  at  this 
time  ascribed  the  Miocene  of  Maryland  to  the  Upper  Marine  and  made 
it  equivalent  to  the  Upper  Tertiary  of  Europe. 

The  following  year  Morton  published  another  paper  in  which  he  pro- 
posed a  classification  of  the  Coastal  Plain  deposits.  In  this  no  distinct 
reference  was  made  to  Maryland,  but  it  is  probable  that  he  still  regarded 
the  Miocene  of  this  State  as  Upper  Marine. 

The  next  paper  of  importance  was  published  by  Conrad,  in  1835,  in 
which  he  assigned  the  Miocene  deposits  to  the  older  Medial  Pleiocene. 
In  the  following  year  Ducatel  referred  the  deposits  of  Calvert  County 
to  older  Pleiocene  and  distinctly  stated  that  they  were  not  Miocene.  He 
also  published  a  map  of  southern  Maryland  in  which  various  deposits 
were  marked  and  the  names  of  the  formations  given  in  red  letters. 

W.  B.  Rogers  was  the  first  to  recognize  the  presence  of  Miocene  de- 
posits in  southern  Maryland.  He  made  the  announcement  in  1836  that 
part  of  the  Maryland  Tertiary  belonging  to  the  Miocene.  He 


\I\KYI..\\I)    GEOLOGICAL    SURVEY  35 

noted  the  great  difference  between  the  fossil  and  living  species, 
showing  that  the  Medial  Tertiary  contained  but  19  per  cent 
of  living  forms.  He  thought  that  the  extermination  was 
due  to  a  fall  of  temperature.  In  the  same  and  following  year  he  de- 
scribed many  fossils  from  the  Miocene  of  southern  Maryland,  and  in 
1842  he  correlated  his  Medial  Tertiary  with  the  Crag  of  England  and 
stated  it  was  Miocene.  The  boundaries  which  he  gave  the  Miocene  at 
that  time  were  not  greatly  different  from  the  boundaries  which  are 
ascribed  to  the  Chesapeake  Group  of  to-day.  In  1844,  Kogers  assigned 
the  diatomaceous  earth  to  a  position  near  the  base  of  the  Miocene. 

About  this  time  much  interest  was  created  in  the  Miocene  problem  of 
Maryland  by  Sir  Charles  Lyell.  He  regarded  these  deposits  as  Miocene, 
and  gave  at  some  length  his  reasons  for  this  opinion.  He  also  stated  that 
the  Miocene  of  Maryland  agreed  more  closely  with  the  Miocene  of  Lor- 
raine and  Bordeaux  than  with  the  Suffolk  Crag.  Lonsdale  also  con- 
cluded from  the  corals  collected  in  the  Miocene  which  were  submitted 
to  him  for  examination,  that  the  American  deposits  were  probably 
accumulated  while  the  climate  was  somewhat  "  superior  "  to  that  of  the 
Crag  and  "  perhaps  "  equal  to  that  of  the  faluns  of  Lorraine,  but  "  in- 
ferior "  to  that  of  Bordeaux.  In  the  same  year  Conrad  described  and 
figured  many  fossils  from  the  Calvert  Cliffs. 

No  more  papers  of  importance  appeared  on  the  Maryland  Miocene 
until  1863,  when  Dana  brought  out  his  first  edition  of  the  Manual  of 
Geology.  In  this  work  he  took  occasion  to  propose  the  term  "  Yorktown 
epoch"  for  the  period  during  which  the  Miocene  of  the  Atlantic  coast 
was  deposited.  The  next  paper  of  significance  was  published  by  Heilprin 
in  1881,  in  which  he  discussed  the  Miocene  at  some  length,  and  divided 
it  into  an  "  Older  period "  and  a  "  Newer  period."  The  Older  period 
contained  the  older  portion  of  the  Miocene  of  Maryland;  and  the  Newer 
period,  the  later  portion.  He  subdivided  the  Newer  period  again  into 
the  Patuxent  Group  and  the  St.  Mary's  Group.  The  next  year,  the  same 
author  revised  his  classification  and  divided  the  Miocene  into  three 
groups  as  follows:  the  Carolinian  or  the  Upper  Atlantic  Miocene,  in- 
cluding the  Sumpter  epoch  of  Dana;  the  Virginian  or  Middle  Atlantic 


36  THE   PHYSICAL   FEATURES   OF    CALVERT    COUNTY 

Miocene,  including  part  of  the  Yorktown  of  Dana  and  the  Newer  group 
of  Maryland;  and  the  Marylandian  or  the  Older  Atlantic  Miocene,  in- 
cluding the  rest  of  Dana's  Yorktown  and  the  older  period  of  Maryland. 
He  suggested  that  the  Virginian  was  of  the  same  age  as  the  second 
Mediterranean  of  Austrian  geologists  and  the  faluns  of  Touraine,  and 
that  the  Marylandian  was,  at  least  in  part,  equivalent  to  the  first  Medi- 
terranean of  Austrian  geologists  and  faluns  of  Leognan  and  Saucats. 
Three  years  later  the  same  author  published  a  map  showing  the  distribu- 
tion of  these  formations  along  the  Atlantic  coast.  In  1888  Otto  Meyer 
took  exception  to  Heilprin's  correlation  and  conclusions,  and  introduced 
the  term  Atlantic  Group  to  embrace  the  Tertiary  of  the  Atlantic  States, 
and  Gulf  Group  for  that  of  the  Gulf  States. 

Three  years  later  Darton  employed  the  term  "  Chesapeake  Group  "  to 
cover  a  portion  of  the  Miocene,  and  in  the  following  year  Dall  and 
Harris  published  their  report  on  the  Miocene  deposits  in  the  Correlation 
Papers  of  the  U.  S.  Geological  Survey,  and  used  the  term  "  Chesapeake 
Group "  to  include  the  Miocene  strata  extending  from  Delaware  to 
Florida.  These  deposits  were  made  during  the  Yorktown  epoch  of 
Dana  and  the  group  included  a  large  part  of  Heilprin's  Marylandian, 
Virginian,  and  Carolinian.  Two  years  later  Harris,  basing  his  work  on 
a  study  of  the  organic  remains  found  in  the  Miocene,  subdivided  the 
Miocene  faunas  of  Maryland  into  the  Plum  Point  fauna,  the  Jones 
Wharf  fauna,  and  the  St.  Mary's  fauna. 

The  following  year  Darton,  by  bringing  together  a  large  number  of 
well  records  throughout  the  Coastal  Plain  from  New  Jersey  southward, 
rendered  a  most  important  service  to  the  study  of  the  Miocene  problem 
in  Maryland  by  suggesting  the  structure  and  extent  of  the  beds  through- 
out the  region.  The  following  year  Dana  admitted  Harris's  faunal 
zones,  but  still  retained  the  term  "  Yorktown,"  to  part  of  which  he  as- 
signed the  Maryland  beds.  In  1896  Darton  published  a  bulletin  under 
the  auspices  of  the  U.  S.  Geological  Survey,  in  which  he  brought  together 
a  large  number  of  well  records  throughout  the  Coastal  Plain.  He  also 
published  the  Nomini  folio,  and  thus  was  the  first  to  express,  on  a  con- 
tour map,  the  development  of  the  Miocene  throughout  a  large  portion 
of  Southern  Maryland. 


MARYLAND   GEOLOGICAL   SURVEY  37 

In  1898  Ball  published  a  most  important  summary  of  existing  knowl- 
edge of  the  Tertiary  of  North  America,  in  which  he  suggested  a  classi- 
fication of  the  Maryland  Miocene  deposits  and  correlated  them  with 
other  parts  of  North  America  and  of  Europe. 

In  Calvert  County  the  Eocene  is  only  slightly  represented  along  the 
south  side  of  Lyons  Creek  and  adjacent  regions  of  the  Patuxent  River. 
A  full  account  of  the  development  of  the  present  knowledge  of  the 
Eocene  in  Maryland  would  involve  a  discussion  of  the  literature  in  regions 
far  beyond  the  borders  of  this  county.  Those  who  desire  to  look  into 
this  subject  are  referred  to  the  Eeport  on  the  Eocene,  by  Clark  and 
Martin,  Maryland  Geological  Survey,  1901,  as  well  as  to  the  reports  of 
the  various  counties  which  lie  within  the  Eocene  belt,  particularly  Anne 
Arundel  and  Prince  George's,  which  are  now  in  preparation.  Many  in- 
vestigators have  contributed  to  the  Eocene  stratigraphy  of  southern 
Maryland,  among  whom  may  be  mentioned  Say,  Conrad,  Morton,  Rogers, 
Lea,  Tyson,  and  Heilprin.  Darton,  in  1891,  included  all  the  Eocene  of 
Maryland  in  one  general  formation  for  which  he  suggested  the  name 
Pamunkey.  Five  years  later,  W.  B.  Clark  discussed  the  Eocene  deposits 
of  the  Middle  Atlantic  slope  both  from  a  stratigraphical  and  paleonto- 
logical  point  of  view.  He  found  the  Eocene  deposits  as  a  whole  divisible 
into  two  stages,  which  were  called  Aquia  Creek  and  Woodstock,  and  these 
again  were  subdivided  into  seventeen  distinct  zones.  In  1901,  Clark 
and  Martin  carried  this  work  still  farther  and  differentiated  the  Eocene 
of  Maryland  into  two  formations,  the  Aquia  and  Nanjemoy.  Each  one 
of  these  formations  was  further  separated  into  two  sub-stages  and  numer- 
ous zones.  A  geologic  map  showing  the  distribution  of  the  two  forma- 
tions throughout  Maryland  was  published  and  the  fossils  found  within 
the  region  were  figured  and  described. 

Throughout  all  southern  Maryland  there  is  a  well-defined  mantle  of 
clay,  loam,  sand,  and  gravel  which  occupies  the  divides  as  well  as  certain 
of  the  larger  valleys.  At  first  this  was  confused  with  the  older  deposits 
on  which  it  lies  and  was  included  with  them  in  all  geological  discussions 
of  the  region.  Little  by  little  it  became  apparent  that  these  surficial 
deposits  were  distinct  in  age  from  the  more  fossiliferous  beds  beneath. 


38          THE  PHYSICAL  FEATURES  OF  CALVERT  COUNTY 

but  the  relation  which  existed  between  them  was  not  understood  and 
little  attention  was  given  to  the  matter.  To  go  into  a  full  discussion  of 
the  history  of  this  separation  would  be  to  repeat  much  that  has  already 
been  said.  Those  who  desire  to  look  into  the  early  history  in  more  detail 
are  referred  to  the  Eeport  on  the  Pliocene  and  Pleistocene  of  Maryland, 
Maryland  Geological  Survey,  1906.  It  was  not  until  Professor  W  J 
McGee  published  his  investigations  of  these  deposits  in  1887  and  1888 
that  their  true  relation  with  the  underlying  formations  was  at  all  under- 
stood. He  gave  the  name  of  Columbia  formation  to  this  entire  series 
of  deposits  and  divided  them  into  fluviatile  and  interfluviatile  phases 
which  he  considered  contemporaneous.  Later,  Darton,  who  took  up  the 
work  where  McGee  left  it,  divided  the  Columbia  formation  of  McGee 
into  an  Earlier  and  a  Later  Columbia.  In  1901,  Shattuck,  who  had 
studied  the  region  in  still  more  detail,  separated  the  same  deposits  into 
three  formations,  the  Sunderland,  Wicomico,  and  Talbot,  which  he  united 
under  the  general  term  Columbia  Group.  He  also  showed  that  these 
were  developed  in  terraces  lying  one  above  the  other  in  order  of  their 
age,  the  oldest  lying  topographically  highest.  The  same  year,  J.  A. 
Bonsteel  and  E.  T.  Avon  Burke  published  a  report  on  the  soils  of 
Calvert  County. 

The  next  year  Shattuck  published  a  report  on  Cecil  County  in  which 
he  referred  to  the  lignite  deposits  of  Calvert  County  and  suggested  an 
explanation  of  their  origin.  In  1904  the  Miocene  deposits  of  Maryland 
were  fully  described  by  Clark,  Shattuck,  Dall,  Glenn,  Martin,  and 
others.  In  this  report  a  geologic  map,  sections  and  many  photographs 
were  published.  The  same  year  the  St.  Mary's  Folio,  by  Shattuck  and 
Miller,  was  published  by  the  U.  S.  Geological  Survey.  This  contained  a 
summary  of  the  geology  of  the  county  and  a  geologic  map  of  its  south- 
ern portion.  Clark  and  Mathews  also  published  a  summary  of  the  physi- 
cal features  and  geology  of  Maryland  in  which  Calvert  County  was  given 
considerable  attention.  Before  the  close  of  the  year  the  report  on  the 
Pliocene  and  Pleistocene  deposits  of  Maryland  appeared  under  the  author- 
ship of  Clark,  Shattuck,  Hollick,  Lucas,  and  others.  In  this  report  the 
surficial  deposits  of  Calvert  County  are  discussed  at  great  length. 


MAKYI.AND    <;!•:(> LOGICAL    SURVEY  39 

BIBLIOGRAPHY. 

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1624. 

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(Repub.)  The  True  Travels,  Adventures  and  Observations  of  Captaine 
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FINCH,   JOHN.     Geological    Essay    on   the   Tertiary    Formations   in 
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42  THE   PHYSICAL   FEATURES   OF    CALVERT    COUNTY 

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2d  Bull.  Proc.  Nat.  Inst.  Prom.  Sci.,  1842,  pp.  192-194,  two  plates. 

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MARYLAND   GEOLOGICAL    SURVEY  43 

1843. 

CONRAD,  T.  A.     Description  of  a  new  Genus,  and  Twenty-nine  new 
Miocene  and  one  Eocene  Fossil  Shells  of  the  United  States. 
Proc.  Acad.  Nat.  Sci.,  Phila.,  vol.  1,  1843,  pp.  305-311. 

1844. 

EOGERS,  WM.  B.     [Tertiary  Infusorial  formation  of  Maryland.] 
Amer.  Jour.  Sci.,  vol.  xlvi,  1844,  pp.  141-142. 

1845. 

CONRAD,  T.  A.  Fossils  of  the  (Medial  Tertiary  or)  Miocene  Forma- 
tion of  the  United  States.  No.  3.  1845.  pp.  57-80.  Plates  xxx-xlv. 

(Repub.)  by  W.  H.  Dall,  Washington,  1893. 

LYELL,  CHAS.  On  the  Miocene  Tertiary  Strata  of  Maryland,  Vir- 
ginia and  of  North  and  South  Carolina. 

Quart.  Jour.  Geol.  Soc.,  London,  vol.  i,  1845,  pp.  413-427. 

Proc.  Geol.  Soc.,  London,  vol.  i,  1845,  pp.  413-427. 

1849. 

BAILEY,  J.  W.  New  Localities  of  Infusoria  in  the  Tertiary  of  Mary- 
land. 

Amer.  Jour.  Sci.,  2d  ser.,  vol.  vii,  1849,  p.  437. 

GIBBES,  E.  W.  Monograph  of  the  fossil  Squalidae  of  the  United 
States. 

Jour.  Acad.  Nat.  Sci.,  Phila.,  2  ser.,  vol.  i,  1849,  pp.  191-206. 

1852. 

FISHER,  E.  S.  Gazetteer  of  the  State  of  Maryland  compiled  from 
the  returns  of  the  Seventh  Census  of  the  United  States.  New  York 
and  Baltimore,  1852,  8vo,  122  pp. 

HIGGINS,  JAMES.  The  Second  Eeport  of  James  Higgins,  M.  D.,  State 
Agricultural  Chemist,  to  the  House  of  Delegates  of  Maryland.  8vo. 
118  pp.  Annapolis,  1852. 

Md.  House  of  Delegates,  Jan.  Sess.,  1852  [C],  8vo,  126  pp. 

1856. 

HIGGINS,  JAMES.  Fifth  Agricultural  Eeport  of  James  Higgins,  State 
Chemist,  to  the  House  of  Delegates  of  the  State  of  Maryland.  8vo. 
91  pp.  Annapolis,  1856  (published  separately). 

Also  Md.  House  of  Delegates,  Jan.  Sess.,  1856. 

Md.  Sen.  Doc. 

Another  edition,  pp.  15-18  omitted,  8vo,  90  pp. 


44          THE  PHYSICAL  FEATURES  OF  CALVERT  COUNTY 

1860. 

TYSON,  P.  T.  First  Keport  of  Philip  T.  Tyson,  State  Agricultural 
Chemist,  to  the  House  of  Delegates  of  Maryland,  Jan.  1860.  8vo.  145 
pp.  Annapolis,  1860.  Maps. 

Md.  Sen.  Doc.  [E].    Md.  House  Doc.  [C]. 

1861. 

CONRAD,  T.  A.  Fossils  of  the  (Medial  Tertiary  or)  Miocene  Forma- 
tion of  the  United  States.  No.  4.  1861  (?).  pp.  81-89,  index  and 
plates  xlv-xlix. 

(Repub.)  by  W.  H.  Ball,  Washington,  1893. 

TYSON,  P.  T.  [Letter  from  Mr.  Tyson  of  Maryland  on  Tripoli.] 
(Read  Dec.,  1860.) 

Proc.  Acad.  Nat.  Sci.,  Phila.,  vol.  xii,  1861,  pp.  550-551. 

1862. 

CONRAD,  T.  A.  Catalogue  of  the  Miocene  Shells  of  the  Atlantic 
Slope. 

Proc.  Acad.  Nat.  Sci.,  Phila.,  vol.  xiv,  1862,  pp.  559-582. 

TYSON,  PHILIP  T.  Second  Report  of  Philip  T.  Tyson,  State  Agricul- 
tural Chemist,  to  the  House  of  Delegates  of  Maryland,  Jan.  1862.  8vo. 
92  pp.  Annapolis,  1862. 

Md.  Sen.  Doc.  [F]. 

1864. 

MEEK,  F.  B.  Check  list  of  the  Invertebrate  Fossils  of  North  America. 
Miocene. 

Smith.  Misc.  Col.,  vol.  vii,  art.  vii,  1864,  32  pp. 

1866. 

CONRAD,  T.  A.  Illustrations  of  Miocene  Fossils,  with  Descriptions  of 
New  Species. 

Amer.  Jour.  Conch.,  vol.  ii,  1866,  pp.  65-74,  plates  3  and  4. 

1867. 

CONRAD,  T.  A.     Descriptions  of  New  Genera  and  Species  of  Miocene 
shells,  with  notes  on  other  fossil  and  recent  species. 
Amer.  Jour.  Conch.,  vol.  iii,  1867,  pp.  257-270. 


MARYLAND   GEOLOGICAL    SUEVEY  45 

HIGGINS,  JAMES.  A  Succinct  Exposition  of  the  Industrial  Besources 
and  Agricultural  advantages  of  the  State  of  Maryland. 

Md.  House  of  Delegates,  Jan.  Sess.,  1867  [DD],  8vo,  109,  iii  pp. 
Md.  Sen.  Doc.,  Jan.  Sess.,  1867  [U]. 

1871. 

SHALER,  N.  S.  On  the  Causes  which  have  led  to  the  Production  of 
Cape  Hatteras. 

Proc.  Boston  Soc.  Nat.  Hist.,  vol.  xiv,  1871,  pp.  110-121. 

1880. 
DANA,  J.  D.     Manual  of  Geology.     3d  edit. 

1881. 

HEILPRIN,  ANGELO.     On  the  Stratigraphical  Evidence  Afforded  by 
the  Tertiary  Fossils  of  the  Peninsula  of  Maryland. 
Proc.  Acad.  Nat.  Sci.,  Phila.,  vol.  xxxii,  1880,  pp.  20-33. 

1882. 

HEILPRIN,  ANGELO.  On  the  relative  ages  'and  classification  of  the 
Post-Eocene  Tertiary  Deposits  of  the  Atlantic  Slope. 

Proc.  Acad.  Nat.  Sci.,  Phila.,  vol.  xxxiv,  1882,  pp.  150-186. 

(Abst.)  Amer.  Jour.  Sci.,  3  ser.,  vol.  xxiv,  1882,  pp.  228-229.  Amer.  Nat., 
vol.  xvii,  1883,  p.  308. 

1884. 

HEILPRIN,  ANGELO.  The  Tertiary  Geology  of  the  Eastern  and 
Southern  United  States. 

Jour.  Acad.  Nat.  Sci.,  Phila.,  2  ser.,  vol.  ix,  1884,  pp.  115-154,  map. 

Contributions  to  the  Tertiary  Geology  and  Paleontology  of 

the  United  States.    4to.    117  pp.,  map.    Phila.,  1884. 

1885. 

WILLIAMS,  JR.  A.  (Editor).     Infusorial  Earth. 
Mineral  Resources  U.  S.,  1883-1884,  Washington,  1885,  p.  720. 

1887. 

DAY,  D.  T.     Infusorial  Earth. 
Mineral  Resources  U.  S.  1886,  Washington,  1887,  p.  537. 


46          THE  PHYSICAL  FEATURES  OF  CALVERT  COUNTY 

1888. 

CLARK,  WM.  B.  On  three  Geological  Excursions  made  during  the 
months  of  October  and  November,  1887,  into  the  southern  counties  of 
Maryland. 

Johns  Hopkins  Univ.  Cir.  No.  63,  vol.  vii,  1888,  pp.  65-67. 

UHLER,  P.  E.     Observations  on  the  Eocene  Tertiary  and  its  Cretaceous 
Associates  in  the  State  of  Maryland. 
Trans.  Md.  Acad.  Sci.,  vol.  i,  1888,  pp.  11-32. 

1890. 

CLARK,  WM.  B.  Third  Annual  Geological  Expedition  into  Southern 
Maryland  and  Virginia. 

Johns  Hopkins  Univ.  Cir.  No.  81,  vol.  ix,  1890,  pp.  69-71. 

BALL,  WM.  H.     Contributions  to  the  Tertiary  Fauna  of  Florida. 
Trans.  Wagner  Free  lust.  Sci.,  Phila.,  vol.  iii,  1890-1895,  570  pp. 

DAY,  D.  T.     Abrasive  Materials. 

Mineral  Resources  U.  S.,  1888,  Washington,  1890. 

UHLER,  P.  R.     Notes  and  Illustrations  to  "  Observations  on  the  Cre- 
taceous and  Eocene  Formations  of  Maryland." 
Trans.  Md.  Acad.  Sci.,  vol.  i,  1890,  pp.  97-104. 

1891. 

CLARK,  WM.  B.  Eeport  on  the  Scientific  Expedition  into  Southern 
Maryland.  [Geology;  W.  B.  Clark.  Agriculture;  Milton  Whitney. 
Archaeology;  W.  H.  Holmes.] 

Johns  Hopkins  Univ.  Cir.  No.  89,  vol.  x,  1891,  pp.  105-109. 

DARTON,  N.  H.  Mesozoic  and  Cenozoic  Formations  of  Eastern  Vir- 
ginia and  Maryland. 

Bull.  Geol.  Soc.  Amer.,  vol.  ii,  1891,  pp.  431-450,  map,  sections. 
(Abst.)  Amer.  Geol.,  vol.  vii,  1891,  p.  185. 
Amer.  Nat,  vol.  xxv,  1891,  p.  658. 

LINDENKOHL,  A.  Notes  on  the  submarine  channel  of  the'  Hudson 
River  and  other  evidences  of  postglacial  subsidence  of  the  middle  Atlantic 
coast  region. 

Amer.  Jour.  Sci.,  3d  ser.,  vol.  xli,  1891,  pp.  489-499,  18  plates. 

McGEE,  W  J     The  Lafayette  Formation. 

12th  Ann.  Kept.  U.  S.  Geol.  Surv.,  1890-91,  Washington,  1891,  pp.  347-521. 


MARYLAND   GEOLOGICAL   SURVEY  47 

WOOLMAN,  LEWIS.  Artesian  wells  and  water-bearing  horizons  of 
Southern  New  Jersey  (with  a  "  note  on  the  extension  southward  of 
diatomaceous  clays  and  the  occurrence  'there  of  flowing  artesian  wells.") 

New  Jersey  Geol.  Surv.,  Rept.  State  Geologist  for  1890,  1891,  pp.  269-276. 

1892. 

CLARK,  WM.  B.     The  Surface  Configuration  of  Maryland. 
Monthly  Rept.  Md.  State  Weather  Service,  vol.  ii,  1892,  pp.  85-89. 

DALL,  W.  H.,  and  HARRIS,  G.  D.     Correlation  Papers — Neocene. 

Bull.  U.  S.  Geol.  Surv.  No.  84,  1892. 

House  Misc.  Doc.,  52d  Cong.,  1st  sess.,  vol.  xliii,  No.  337. 

DAY,  D.  T.  (Editor).     Infusorial  Earth. 

Mineral  Resources  U.  S.,  1889-90,  Washington,  1892,  p.  459. 

The  statistics  for  the  year  are  also  given  In  the  Eleventh  Census. 

SCHARF,  J.  THOMAS.  The  Natural  Resources  and  Advantages  of 
Maryland,  being  a  complete  description  of  all  the  counties  of  the  State 
and  the  City  of  Baltimore.  Annapolis,  1892. 

1893. 

CLARK,  W.  B.  Physical  Features  [of  Maryland],  pp.  11-54  of  Mary- 
land, its  Kesources,  Industries  and  Institutions.  Baltimore,  1893. 

DALL,  WM.  H.  Republication  of  Conrad's  Fossils  of  the  Medial 
Tertiary  of  the  United  States.  Phila.,  1893. 

DARTON,  N.  H.    Cenozoic  History  of  Eastern  Virginia  and  Maryland. 

Bull.  Geol.  Soc.  Amer.,  vol.  v,  1893,  p.  24. 

(Abst.)  Amer.  Jour.  Sci.,  3d  ser.,  vol.  xlvi,  1893,  p.  305. 

HARRIS,  G.  D.     The  Tertiary  Geology  of  Calvert  Cliffs,  Maryland. 
Amer.  Jour.  Sci.,  3d  ser.,  vol.  xlv,  1893,  pp.  21-31,  map. 

-  Eepublication  of  Conrad's  Fossil  Shells  of  the  Tertiary  For- 
mations of  North  America.  8vo.  121  pp.  20  plates.  Washington, 
D.  C.,  1893 

WHITNEY,  MILTON.     The  Soils  of  Maryland. 

Md.  Agri.  Exper.  Sta.,  Bull.  No.  21,  College  Park,  1893,  58  pp.,  map. 

WILLIAMS,  G.  H.     Mines  and  Minerals  [of  Maryland]. 
Maryland,    its    Resources,    Industries,    and    Institutions,    Baltimore,    1893, 
pp.  89-153. 


48  THE   PHYSICAL    FEATUEES   OF    CALVERT    COUNTY 

WILLIAMS,  G.  H.,  and  CLARK,  W.  B.     Geology  [of  Maryland]. 
Maryland,  its  Resources,  Industries,  and  Institutions,  Baltimore,  1893,  pp. 
55-89. 

1894. 

CLARK,  WM.  BULLOCK.  The  Climatology  and  Physical  Features  of 
Maryland. 

1st  Biennial  Kept.  Md.  State  Weather  Service,  1894. 

DARTON,  N".  H.  An  outline  of  the  Cenozoic  History  of  a  Portion  of 
the  Middle  Atlantic  Slope. 

Jour.  Geol.,  vol.  ii,  1894,  pp.  568-587. 

—  Artesian  Well  Prospects  in  Eastern  Virginia,  Maryland,  and 
Delaware. 

Trans.  Amer.  Inst.  Min.  Eng.,  vol.  xxiv,  1894,  pp.  372-397,  plates  1  and  2. 

—  Fredericksburg  Folio.     Explanatory  sheets. 

U.  S.  Geol.  Surv.  Geol.  Atlas,  folio  No.  13,  Washington,  1894. 

1896. 

BARTON,  1ST.  H.  Artesian  Well  Prospects  in  the  Atlantic  Coastal 
Plain  Eegion. 

Bull.  U.  S.  Geol.  Surv.,  No.  138,  1896,  .228  pp.,  19  plates. 
House  Misc.  Doc.,  54th  Cong.,  2d  sess.,  vol.  — ,  No.  28. 

—  Nomini  Folio,  Explanatory  sheets. 

U.  S.  Geol.  Surv.,  Geol.  Atlas,  folio  23,  Washington,  1896. 

1897. 

BAUER,  L.  A.     First  Eeport  upon  the  Magnetic  Work  in  Maryland, 
including  the  History  and  Objects  of  Magnetic  Surveys. 
Md.  Geol.  Surv.,  vol.  i,  1897,  pp.  403-529,  plates  xiv-xvii. 

CLARK,  WM.  BULLOCK.  Historical  Sketch,  embracing  an  Account  of 
the  Progress  of  Investigation  concerning  the  Physical  Features  and 
Natural  Eesources  of  Maryland. 

Md.  Geol.  Surv.,  vol.  i,  1897,  pp.  48-138,  plates  ii-v. 

—  Outline  of  Present  Knowledge  of  the  Physical  Features  of 
Maryland. 

Ibid.,  vol.  i,  1897,  pp.  139-228,  plates  vi-xiii. 

MARYLAND  GEOLOGICAL  SURVEY,  Volume  One. 

The  Johns  Hopkins  Press,  1897.    539  pp.    Plates  and  maps. 


MARYLAND   GEOLOGICAL    SURVEY  49 

MATHEWS,  EDWARD  B.  Bibliography  and  Cartography  of  Maryland, 
including  Publications  relating  to  the  Physiography,  Geology  and  Min- 
eral Eesources. 

Md.  Geol.  Surv.,  vol.  i,  1897,  pp.  229-401. 

1898. 

CLARK,  WILLIAM  BULLOCK.     Administrative  Keport. 
Md.  Geol.  Surv.,  vol.  ii,  1898,  pp.  25-47. 

DALL,  W.  H.  A  Table  of  the  North  American  Tertiary  Horizons, 
correlated  with  one  another  and  with  those  of  western  Europe,  with 
Annotations.  , 

18th  Ann.  Kept.  U.  S.  Geol.  Surv.,  1896-97,  Washington,  1898,  pp.  323-348. 

MARYLAND  GEOLOGICAL  SURVEY.     Volume  Two. 
The  Johns  Hopkins  Press,  1898.    509  pp.    Plates  and  maps. 

MATHEWS,  EDWARD  B.  An  Account  of  the  Character  and  Distribu- 
tion of  Maryland  Building  Stones,  together  with  a  History  of  the 
Quarrying  Industry. 

Md.  Geol.  Surv.,  vol.  ii,  1898,  pp.  125-245. 

—  The  Maps  and  Map-Makers  of  Maryland. 
Ibid.,  pp.  337-488,  plates  vii-xxxii. 

MERRILL,  GEORGE  P.  The  Physical,  Chemical  and  Economic  Proper- 
ties of  Building  Stones. 

Ibid.,  vol.  ii,  1898,  pp.  47-125,  plates  iv-vi. 

SHATTUCK,  G.  B.  Two  Excursions  with  Geological  Students  into  the 
Coastal  Plain  of  Maryland. 

Johns  Hopkins  Univ.  Cir.  No.  137,  vol.  xv,  1898,  pp.  15-16. 

1899. 

ABBE,  CLEVELAND,  JR.  A  General  Keport  on  the  Physiography  of 
Maryland. 

Md.  Weather  Service,  vol.  i,  1899,  pp.  41-216,  plates  i-xix. 

CLARK,  WILLIAM  BULLOCK.     The  Eelations  of  Maryland  Topography, 
Climate  and  Geology  to  Highway  Construction. 
Md.  Geol.  Surv.,  vol.  iii,  1899,  pp.  47-107,  plates  iii-xi. 

JOHNSON,  ARTHUR  NEWHALL.  The  Present  Condition  of  Maryland 
Highways. 

Ibid.,  pp.  187-263,  plates  xv-xxviii. 


50  THE   PHYSICAL   FEATURES   OF    CALVERT    COUNTY 

MARYLAND  GEOLOGICAL  SURVEY.     Volume  Three. 

The  Johns  Hopkins  Press,  Baltimore,  1899,  461  pp.       Plates  and  maps. 

SIOUSSAT,  ST.  GEORGE  LEAKIN.     Highway  Legislation  in  Maryland, 
and  its  Influence  on  the  Economic  Development  of  the  State. 
Ibid.,  pp.  107-187,  plates  xii-xiv. 

1901. 

BONSTEEL,  J.  A.,  and  BURKE,  E.  T.  AVON.  Soil  Survey  of  Calvert 
County,  Md. 

Field  Oper.  Div.  Soils  for  1900,  U.  S.  Dept.  Agri.,  Second  Kept.  Div.  Soils, 
1901,  pp.  147-171,  with  map. 

CLARK,  WILLIAM  BULLOCK,  and  MARTIN,  GEORGE  CURTIS.  The 
Eocene  Deposits  of  Maryland. 

Md.  Geol.  Surv.,  Eocene,  1901,  pp.  19-92,  plates  i-ix. 

— . Systematic  Paleontology,  Mollusca. 

Ibid.,  pp.  122-203,  plates  xvii-lviii. 

MARYLAND  GEOLOGICAL  SURVEY.  Maryland  and  its  Natural  Ee- 
scurces. 

Official  Publication  of  the  Maryland  Commissioners,  Pan-American  Expo- 
sition, Baltimore,  1901,  38  pp.,  map. 

MARYLAND  GEOLOGICAL  SURVEY.  Maryland  and  its  Natural  Ee- 
sources. 

Official  Publication  of  the  Maryland  Commissioners,  Inter-state  West 
Indian  Exposition,  Baltimore,  1901,  38  pp.,  map. 

SHATTUCK,  GEORGE  BURBANK.  The  Pleistocene  Problem  of  the  North 
Atlantic  Coastal  Plain. 

Johns  Hopkins  Univ.  Circ.,  vol.  xx,  1901,  pp.  69-75. 
Amer.  Geol.,  vol.  xxviii,  1901,  pp.  87-107. 

1902. 

BAUER,  L.  A.     Second  Eeport  on  Magnetic  Work  in  Maryland. 
Md.  Geol.  Surv.,  vol.  v,  Baltimore,  1902,  pp.  23-98.     With  maps. 

MARYLAND  GEOLOGICAL  SURVEY.     Volume  Four. 
The  Johns  Hopkins  Press,  Baltimore,  1902. 

Maryland  Geological  Survey  in  co-operation  with  U.  S.  Bureau  of 
Soils.  Map  of  Calvert  County  showing  the  Agricultural  Soils.  Pub- 


MARYLAND   GEOLOGICAL   SURVEY  51 

lished  on  topographic  base,  prepared  for  Md.  Geol.  Surv.  by  U.  S.  Geol. 
Surv. 

25£  x  38£,  contour  20  feet,  8  colors  and  patterns,  scale  1/62,500. 

NEWTON,  K.   BULLEN.     List  of  Thomas   Say's  types  of  Maryland 
(U.  S.)  mollusca  in  the  British  Museum. 
Geol.  Mag.,  dec.  iv,  vol.  ix,  1902,  pp.  303-305. 

RIES,  HEINRICH.     Keport  on  the  Clays  of  Maryland. 
Md.  Geol.  Surv.,  vol.  iv,  1902,  pp.  203-505. 

1903. 

Maryland  Geological  Survey  in  co-operation  with  U.  S.  Geological 
Survey.  Map  of  Calvert  County  showing  the  geological  formations. 
[Revised  edition.]  Published  on  topographic  base,  prepared  for  Md.  Geol. 
Surv.  by  U.  S.  Geol.  Surv. 

25£  x  38£,  contour  20  feet,  7  colors  and  patterns,  scale  1/62,500. 

Earlier  edition  appeared  in  1902. 

1904. 

BAGG,  RUFUS  M.,  JR.  Systematic  paleontology  of  the  Miocene  de- 
posits of  Maryland :  Foraminif era. 

Md.  Geol.  Surv.,  Miocene,  pp.  460-483,  plates  cxxxi-cxxxiii,  1904. 

BOYER,  C.  S.     Thallophyta-Diatomaceae. 

Md.  Geol.  Surv.,  Miocene,- pp.  487-507,  plates  cxxxiv,  cxxxv,  1904. 

CASE,  E.  C.     Mammalia,  Aves,  Reptilia. 

Md.  Geol.  Surv.,  Miocene,  pp.  3-70,  plates  x-xxvii,  1904. 

CLARK,  WILLIAM  BULLOCK.     The  Miocene  deposits  of  Maryland.  In- 
troduction and  general  stratigraphic  relations. 
Md.  Geol.  Surv.,  Miocene,  pp.  xxiii-xxxii,  1904. 

•  Echinodermata. 

Md.  Geol.  Surv.,  Miocene,  pp.  430-433,  plates  cxix,  cxx,  1904. 

DALL,  W.  H.  The  Relations  of  the  Miocene  of  Maryland  to  that  of 
other  regions  and  to  the  recent  fauna. 

Md.  Geol.  Surv.,  Miocene,  pp.  cxxxix-clv,  1904. 
Abstract:   Science,  new  ser.,  vol.  xix,  pp.  502-503,  1904. 

EASTMAN,  C.  R.    Pisces. 

Md.  Geol.  Surv.,  Miocene,  pp.  71-93,  plates  xxviii-xxxii,  1904. 


52          THE  PHYSICAL  FEATURES  OF  CALVERT  COUNTY 

GLENN,  L.  C.     Pelecypoda. 

Md.  Geol.  Surv.,  Miocene,  pp.  274-401,  plates  Ixv-cviii,  1904. 

HOLLICK,  ARTHUR.     Angiospermse. 

Md.  Geol.  Surv.,  Miocene,  pp.  483-486,  Fig.  1,  1904. 

MARTIN,  G.  C.  Malacostraca,  Cirripedia,  Mollusca  (except  Pele- 
cypoda), Brachiopoda,  Vermes,  Eadiolaria. 

Md.  Geol.  Surv.,  Miocene,  pp.  94-97,  130-274,  402-404,  430,  447-459,  plates 
xxxiii-xxxiv,  xxxix-lxiv,  cix,  cxviii,  cxxx. 

SHATTUCK,  GEORGE  BURBANK.     Geological  and  Paleontological  Ee- 
lations,  with  a  Eeview  of  Earlier  Investigations. 
Md.  Geol.  Surv.,  Miocene,  pp.  xxxiii-cxxxvii,  1904. 

ULRICH,  E.  0.     Hydrozoa. 

Md.  Geol.  Surv.,  Miocene,  pp.  433-438,  plate  cxxi,  1904. 

—  and  BASSLER,  E.  S.     Ostracoda,  Bryozoa. 

Md.  Geol.  Surv.,  Miocene,  pp.  98-130,  404-429,  plates  xxxv-xxxvii,  cix-cxviii, 
1904. 

VAUGHAN,  T.  W.     Anithozoa. 

Md.  Geol.  Surv.,  Miocene,  pp.  438-447,  plates  cxxii-cxxix,  1904. 

1906. 

CLARK,  WILLIAM  BULLOCK  and  MATHEWS,  EDWARD  B.  Beport  on 
the  Physical  Features  of  Maryland. 

Md.  Geol.  Surv.,  vol.  vi,  part  i,  pp.  27-259,  plates  i-xxiii,  1906. 

CLARK,  WM.  BULLOCK,  HOLLICK,  ARTHUR,  and  LUCAS,  FREDERIC 
A.  The  Interpretation  of  the  Paleontological  Criteria. 

Md.  Geol.  Surv.,  Pliocene  and  Pleistocene,  pp.  139-152,  plates  xxxii,  xxxiii, 
1906. 

CLARK,  W.  B.     Crustacea,  Mollusca,  Coelenterata,  Protozoa. 
Md.  Geol.  Surv.,  Pliocene  and  Pleistocene,  pp.  173-210,  213-216,  plates  xli-lxvi, 
1906. 

HAY,  0.  P.     Eeptilia. 

Md.  Geol.  Surv.,  Pliocene  and  Pleistocene,  pp.  169,  170,  pi.  xl,  1906. 

HOLLICK,  ARTHUR.     Pteridophyta,  Spermatophyta. 

Md.  Geol.  Surv.,  Pliocene  and  Pleistocene,  pp.  217-237,  plates  Ixvii-lxxv,  1906. 

LUCAS,  F.  A.     Mammalia. 

Md.  Geol.  Surv.,  Pliocene  and  Pleistocene,  157-169,  plates  xxxiv-xl,  1906. 


MARYLAND   GEOLOGICAL   SURVEY  53 

SELLARDS,  E.  H.     Insecta. 

Md.  Geol.  Surv.,  Pliocene  and  Pleistocene,  pp.  170-172,  pi.  xl,  1906. 

SHATTUCK,   GEORGE  BURBAXK.     The  Pliocene  and   Pleistocene  De- 
posits of  Maryland. 

Md.  Geol.  Surv.,  Pliocene  and  Pleistocene,  pp.  23-152,  plates  i-xxxi,  1906. 
SHATTUCK,  GEO.  B.,  and  MILLER,  B.  L. 

St.  Mary's  Folio. 

U.  S.  Geol.  Surv.  Geol.  Atlas,  folio  No.  136,  Washington,  1906. 

TRUE,  FREDERICK  W.     Description  of  a  new  genus  and  species  of 
fossil  seal  from  the  Miocene  of  Maryland. 

Proc.  U.  S.  Natl.  Museum,  vol.  xxx,  pp.  835-840,  plates  Ixxv-lxxvi,  1906. 

ULRICH,  E.  0.     Molluscoidea. 

Md.  Geol.  Surv.,  Pliocene  and  Pleistocene,  pp.  210-212,  fig.  10,  1906. 


THE  PHYSIOGRAPHY  OF  CALVERT  COUNTY 

BY 

GEORGE  BURBANK  SHATTUCK 


INTRODUCTORY. 

In  the  main,  there  are  two  methods  of  discussing  the  physical  features 
of  a  region.  The  first  and  older  method  is  to  describe  in  great  detail 
the  various  topographic  features  which  the  region  possesses,  without  re- 
gard to  their  origin,  mutual  relations,  or  significance.  This  method  has 
its  place  and  is  still  used  to-day,  but  is  at  best  a  mere  catalogue  of 
geographic  facts.  The  second  and  modern  method  of  discussing  the 
topography  of  a  region  begins  where  the  former  leaves  off.  It  assumes 
a  knowledge  of  the  leading  physical  features  and  seeks  to  point  out  the 
relations  which  they  bear  to  one  another  as  well  as  the  causes  which 
have  brought  them  into  existence.  It  will  be  seen  that  the  latter  is  the 
more  scientific  of  the  two.  In  discussing  the  physiography  of  Calvert 
County,  both  methods  will  be  employed.  The  topographic  history  of 
Calvert  County,  although  complex  and  extremely  interesting  is  not  as 
diversified  as  that  of  many  of  the  other  counties  of  Maryland.  The 
reason  for  this  is  found  in  the  fact  that  the  county  lies  entirely  within 
the  Coastal  Plain,  while  many  of  the  other  counties  of  Maryland  lie  in 
more  than  one  physiographic  province.  It  is  a  matter  of  regret  that  the 
geologic  record  of  Calvert  County  is  so  imperfect  that  many  of  the  earlier 
episodes  in  its  history  have  been  lost  entirely  or  can  only  be  partially 
recovered.  Other  and  later  portions  of  its  historical  record,  however, 
are  so  much  more  complete  that  they  can  be  read  in  their  leading  features 
as  easily  as  if  they  had  recently  occurred.  In  discussing  the  physiography 
of  Calvert  County,  the  topography  of  the  region  will  be  first  described 
and  then  the  geologic  history  which  has  brought  about  the  principal  sur- 
face features  will  be  outlined. 


56  THE  PHYSIOGRAPHY  OF  CALVERT  COUNTY 

TOPOGRAPHIC  DESCRIPTION. 

Maryland  may  be  considered  as  divisible  into  three  grand  physio- 
graphic provinces  which  are,  beginning  with  the  eastern,  the  Coastal 
Plain,  the  Piedmont  Plateau,  and  the  Appalachian  Eegion.  The  Coastal 
Plain  extends  from  the  outer  margin  of  the  continental  shelf  westward  to 
the  edge  of  the  Piedmont  Plateau,  or  approximately  to  the  position  occu- 
pied by  the  Baltimore  &  Ohio  Eailroad  as  it  crosses  the  State  from 
Delaware  to  Washington.  The  relief  throughout  the  Coastal  Plain  re- 
gion is  low  and  its  western  margin  slowly  rises  to  an  altitude  of  about 
300  to  400  feet  as  it  merges  with  the  Piedmont  Plateau.  The  Pied- 
mont Plateau  extends  from  the  western  margin  of  the  Coastal  Plain  to 
the  eastern  boundary  of  the  Appalachian  region.  It  is  considerably 
higher  than  the  Coastal  Plain,  attaining  in  Carroll  County  an  altitude 
of  over  800  feet,  and  has  been  deeply  dissected  by  the  river  valleys  which 
cross  it.  Its  western  border  merges  with  the  Appalachian  region  at 
Catoctin  Mountain.  The  Appalachian  region  occupies  the  remainder  of 
the  State.  It  consists  of  parallel  ridges  of  rugged  mountains  over  3000 
feet  in  height,  separated  by  broad  valleys  and  crossed  by  narrow  water 
gaps.  Many  of  the  counties  of  Maryland  present  a  variety  of  topo- 
graphic features  resulting  from  the  fact  that  they  lie  in  more  than  one 
of  these  regions.  Calvert  County,  however,  lies  entirely  within  the 
Coastal  Plain  and  it  is  due  to  this  fact  that  its  scenery,  although  pictur- 
esque and  in  a  measure  diversified,  does  not  present  the  variety  which 
is  found  in  some  of  the  other  counties  of  Maryland.  In  a  report  on 
Cecil  County  *  recently  published,  two  types  of  the  typographic  character- 
istics of  the  Coastal  Plain  were  defined.  They  were  described  in  the 
following  words :  "  In  Cecil  County  the  Coastal  Plain  contains  two  con- 
trasted types  of  topography.  One  type  is  a  flat,  low,  featureless  plain, 
and  the  other  is  a  rolling  upland  attaining  four  times  the  elevation  of 
the  former  and  resembling  the  topography  of  the  Piedmont  Plateau 
more  than  that  typical  of  the  Coastal  Plain.  Elk  Kiver  is  the  dividing 
line  between  these  two  types  of  topography.  On  the  east  side  of  it  is 

1  Cecil  County,  Maryland  Geological  Survey,  1902. 


MARYLAND  GEOLOGICAL  SURVEY. 


CALVERT  COUNTY,  PLATE 


FlG.    I. — VIEW    SHOWING   CALVERT   FORMATION    AT    MOUTH    OF   PARKER   CREEK. 


FlG.    2. — VIEW    SHOWING 


OF    TO1XT   OF 


MARYLAND   GEOLOGICAL   SURVEY  57 

the  low  land  of  the  typical  Coastal  Plain  and  on  the  west  of  it  are  the 
rolling  uplands." 

Calvert  County  contains  only  one  type  of  Coastal  Plain  topography, 
which  is  the  Western  Shore  type.  Its  former  level  surface  has 
been  so  extensively  dissected,  however,  by  the  streams  which  run  east 
into  Chesapeake  Bay  and  west  into  the  Patuxent  Eiver  that  the  country 
now  possesses  the  character  of  a  rolling  upland,  such  as  is  customary  to 
associate  with  the  eastern  margin  of  the  Piedmont  Plateau.  The  sur- 
face, although  resembling  a  dissected  plain,  is  in  reality  made  up  of 
three  distinct  systems  of  terraces,  which  lie  above  one  another  like  steps 
in  a  flight  of  stairs.  The  oldest,  which  is  topographically  highest,  occu- 
pies the  center  and  the  other  terraces  are  grouped  about  it  in  concentric 
arrangement  in  order  of  their  age. 

The  oldest  terrace,  having  been  subjected  to  erosion  longer  than  the 
others,  is  more  dissected  and  its  surface,  which  was  originally  level,  has 
now  been  modified  so  as  to  present  a  gently  rolling  aspect.  The  next 
younger  terrace,  although  it  also  has  suffered  from  erosion  has  not  yet 
reached  the  advanced  stage  of  the  oldest,  while  the  terrace  which  is 
topographically  lowest  and  therefore  the  youngest  of  the  three  has  suf- 
fered least  of  all  by  erosion  and,  in  fact,  has  been  subjected  to  the  work 
of  streams  for  so  short  a  time  that  its  surface  for  the  most  part  retains 
its  originally  level  and  unbroken  character. 

Each  of  these  terraces  is  separated  from  the  one  just  below  by  a  well- 
defined  scarp-line  similar  in  appearance  to  the  sea-cliff  which  separates 
the  lowest  terrace  from  the  modern  beach.  In  approaching  the  main 
divide  of  Calvert  County  from  the  shore  of  the  Patuxent  Eiver,  one 
travels  for  some  distance  over  an  unbroken  flat,  which  constitutes  the 
lowest  and  youngest  terrace.  The  surface  of  this  plain  gradually  rises 
toward  the  interior.  At  its  inner  margin,  which  is  about  45  feet  in 
height,  it  is  terminated  by  an  abrupt  scarp  of  10  to  20  feet,  which  leads 
up  to  the  surface  of  the  middle  terrace.  This  also  is  a  flat,  lying  higher 
than  the  former  and  extensively  eroded  by  the  headwaters  of  streams 
which  rise  within  it.  This  middle  flat  in  its  turn  gently  rises  toward  the 
interior  until  at  a  height  of  about  75  or  80  feet  it  is  terminated  by  a 
5 


58  THE    PHYSIOGRAPHY    OF    CALVERT    COUNTY 

second  scarp  some  20  to  30  feet  in  height,  which  hlends  at  its  upper 
edge  with  the  rolling  surface  of  the  highest  and  oldest  terrace.  The 
latter  is  the  main  divide  of  the  county,  and  in  the  northern  portion  of 
the  region  at  Mount  Harmony  it  attains  its  greatest  elevation.  Here 
the  surface  stands  at  a  height  of  about  180  feet. 

This  ideal  arrangement  of  the  three  terrace  systems  surrounding  each 
other  in  concentric  plains  in  order  of  their  age  is  typical  but  not  every- 
where present.  The  three  systems  can  be  seen  in  their  normal  develop- 
ment almost  anywhere  in  the  Patuxent  basin  of  Calvert  County,  but  on 
the  eastern  slope  of  the  region  the  waves  of  Chesapeake  Bay  have 
advanced  so  extensively  on  the  land  that  one  or  both  of  the  two  lower 
terraces  have  frequently  been  eliminated  by  erosion.  From  Cove  Point 
to  Chesapeake  Beach  there  is  a  high  wave-cut  scarp  known  as  the  Calvert 
Cliffs  which  is  capped  by  the  oldest  terrace.  Only  at  intervals  do  rem- 
nants of  the  two  younger  terraces  occur  to  show  that  they  formerly  ex- 
isted here  in  much  greater  development. 

The  great  difference  in  the  erosive  power  of  the  waves  of  the  Chesa- 
peake Bay  and  of  the  waves  of  the  Patuxent  River  has  produced  one  of 
the  most  striking  topographic  features  in  the  county.  Along  the  Pa- 
tuxent Eiver,  low  shores  gently  rising  toward  the  interior  are  the  rule. 
The  only  exceptions  to  this  being  found  at  Hollin  Cliff  and  at  Lyons 
Creek  Wharf.  At  Hollin  Cliff  the  tidal  current  of  the  Patuxent  River 
has  scoured  the  eastern  bank  removing  the  lower  terrace  and  producing 
a  cliff  60  to  70  feet  in  height.  At  Lyons  Creek  Wharf  the  relief  does 
not  exceed  60  feet.  On  the  bay  shore  the  incessant  pounding  of  the 
waves  has  produced  the  almost  unbroken  line  of  cliffs  just  mentioned, 
which  extend  a  distance  of  30  miles  from  Chesapeake  Beach  to  Drum 
Point  and  rise  in  many  places  to  over  100  feet  in  height.  In  three 
localities  only  is  this  feature  masked  by  remnants  of  the  lower  terraces 
which  still  cling  to  the  base  of  the  cliffs.  One  of  these  is  found  in  the 
vicinity  of  Dares  Wharf  where  the  shore  line  for  a  distance  of  four  miles 
is  fringed  with  a  remnant  of  the  lowest  terrace.  Another  locality  is 
between  Point  of  Rocks  and  Cove  Point,  where  not  only  are  the  lower 
terraces  present,  but  also  a  change  in  the  direction  of  the  shore  current 


MARYLAND   GEOLOGICAL    SURVEY  59 

has  produced  an  extensive  sand  spit,  known  as  Cove  Point.  The  third 
and  last  locality  is  in  the  vicinity  of  Drum  Point,  where  the  low  terraces 
which  line  the  Patuxent  Eiver  terminate  abruptly  on  the  bay  shore. 

To  the  three  terraces  just  described,  a  fourth  may  be  added,  although 
it  does  not  form  a  conspicuous  element  in  the  topography.  This  fourth 
terrace  is  the  beach  and  the  wave-built  flat  which  extends  out  along  the 
shores  of  the  Patuxent  Eiver  and  Chesapeake  Bay.  It  is  everywhere 
present,  and  its  width  depends  in  a  large  measure  upon  the  force  of  the 
tidal  currents  which  sweep  over  it. 

Taken  as  a  whole,  the  divide  of  the  county  is  lowest  in  its  southeastern 
portion  between  Cove  Point  and  Hellen  Creek,  where  it  has  an  elevation 
of  only  12?  feet;  from  this  point  it  rises  gently  until  it  attains  its  high- 
est altitude  in  the  vicinity  of  Mt.  Harmony  near  the  northern  edge  of 
the  county,  where  it  reaches  a  height  of  about  180  feet. 

THE  DRAINAGE  OF  CALVERT  COUNTY. 

Calvert  County,  occupying  as  it  does  the  southern  extension  of  one  of 
the  largest  peninsulas  in  southern  Maryland,  is  entirely  surrounded  by 
water  except  along  its  northern  border,  where  it  abuts  against  Anne 
Arundel  County.  Its  eastern  margin  is  washed  by  the  waves  of  Chesa- 
peake Bay  and  its  western  and  southern  margins  terminate  with  the 
Patuxent  River.  These  two  bodies  of  water  receive  the  drainage  of  the 
entire  county.  The  divide  which  separates  the  headwaters  of  the  streams 
which  flow  into  Chesapeake  Bay  on  the  east  and  the  Patuxent  River  on 
the  west  is  an  extremely  circuitous  line  (see  map).  It  enters  Calvert 
from  Anne  Arundel  County  at  a  point  almost  three  miles  from  the  bay 
shore.  From  here  it  runs  south  and  then  southwest  to  Mt.  Harmony. 
From  this  point  it  extends  due  south  to  the  lower  Marlboro-Prince  Fred- 
erick district  line  and  then  runs  due  east  along  the  district  line  to  The 
Willows.  South  from  The  Willows  to  Prince  Frederick  the  divide 
describes  the  letter  S,  and  from  Prince  Frederick  to  Port  Republic 
follows  very  closely  the  line  of  the  proposed  Baltimore  and  Drum  Point 
Railroad.  At  Port  Republic  it  runs  rapidly  eastward,  striking  the  bay 
shore  about  a  mile  west  of  Point  of  Rocks.  Here  it  advances  inland 


60  THE   PHYSIOGRAPHY   OF    CALVERT    COUNTY 

somewhat  and  then  again  runs  out  eastward  to  Little  Cove  Point  and 
then  southward  again  to  Drum  Point.  Although  this  divide  describes  a 
most  circuitous  line,  it  is  throughout  its  entire  extent  situated  to  the 
east  or  the  Chesapeake  side  of  the  central  line  of  the  county.  In  only 
two  places  does  it  approach  this  middle  line  and  it  usually  lies  well  over 
toward  the  shore  of  Chesapeake  Bay,  particularly  in  the  southern  half  of 
the  county. 

As  would  be  expected  from  the  position  of  the  divide,  the  streams 
which  empty  into  Chesapeake  Bay  are  very  much  shorter  than  those 
which  find  their  way  into  the  Patuxent  River.  The  most  important  of 
the  former  drainage  lines  are  Fishing  Creek  and  Parker  Creek,  while 
among  the  streams  which  empty  into  the  Patuxent  Eiver  should  be 
mentioned  Lyons,  Hall,  Cocktown,  Hunting,  Battle,  Island,  St.  Leonard, 
Hellen,  and  Mill  creeks.  Fishing  Creek  and  Parker  Creek  were  formerly 
estuaries,  but  their  lower  courses  have  now  been  filled  and  transformed 
into  marshes.  Among  the  streams  which  empty  into  the  Patnxent  River, 
Hunting,  Battle,  Island,  St.  Leonard,  Hellen,  and  Mill  creeks  are  all 
estuaries  through  their  lower  portions. 

Another  fundamental  difference  is  to  be  noted  between  the  streams  on 
either  side  of  the  central  divide.  Those  which  empty  into  the  Patuxent 
River  not  only  are  longer  and  are  converted  into  estuaries  throughout 
their  lower  portions  as  explained  above,  but  also  are  bordered  extensively 
along  their  lower  reaches  by  the  two  lower  terraces.  Their  headwaters 
usually  flow  in  steep  valleys,  but  their  lower  courses  are  tidal  and  are 
bordered  by  low  banks  which  rise  gradually  to  higher  land  situated  some- 
what distant  from  their  shores.  On  the  Chesapeake  side  of  the  divide 
the  streams  are  short,  steep,  rapid  and  flow  through  steepsided  gorges. 
Some  of  them,  in  fact,  have  not  yet  been  able  to  sink  their  valleys  to  the 
level  of  the  Bay  shore  and  cascade  50  feet  or  more  from  the  mouths  of 
their  valleys  to  the  beach  below. 

The  reason  for  this  striking  difference  between  the  character  of  the 
streams  flowing  eastward  into  the  Chesapeake  and  those  flowing  west- 
ward into  the  Patuxent  seems  to  be  entirely  due  to  the  greater  erosive 
power  of  the  waves  of  the  Chesapeake  as  compared  with  those  of  the 


MARYLAND   GEOLOGICAL   SURVEY  61 

Patuxent  River.  It  will  be  remembered  in  describing  the  distribution 
of  the  terraces  in  a  previous  section  that  the  presence  of  the  two  lower 
terraces  along  the  Patuxent  River  and  their  absence  on  the  Bay  shore  was 
mentioned.  This  absence  of  terraces  along  the  Chesapeake  shore  is  doubt- 
less due  to  their  removal  by  erosion  for  the  same  forces  which  carried 
away  the  terraces  have  also  cut  rapidly  back  into  the  soft,  yielding, 
unconsolidated  material  which  composes  the  entire  region  and  have  not 
only  produced  a  straight  coast  line,  but  have  also  cut  back  so  rapidly 
that  the  mouthward  portions  of  what  used  to  be  considerable  streams 
have  been  carried  away,  leaving  only  their  headwaters  as  weak,  short 
brooks,  some  of  which  are  unable  to  sink  their  valleys  down  to  the  level 
of  the  beach  as  fast  as  the  waves  can  cut  back  toward  their  valleys.  Others 
have  still  enough  force  to  maintain  their  mouth  at  sea  level  by  descending 
rapidly  through  narrow  and  steep-walled  gorges.  The  divide  at  one 
time  probably  occupied  about  the  center  of  the  peninsula.  Its  present 
position  seems  to  be  due  to  the  greater  erosive  powers  of  Chesapeake  Bay 
and  the  rapid  advance  of  the  shore  line  toward  this  divide. 

THE  STRUCTURE  OF  THE  COASTAL  PLAIN. 

The  materials  of  which  this  region  is  built  consist  of  clay,  loam,  sands, 
gravel,  and  boulders.  These  deposits,  are  loose  and  unconsolidated,  ex- 
cept where  local  ledges  of  ironstone  have  been  developed.  Although  the 
materials  which  have  built  up  Calvert  County  have  been  deposited  at 
various  times  and  belong  to  a  large  number  of  geological  horizons,  still 
they  all  lie  either  horizontal  or  nearly  so.  Those  which  have  been  tilted 
most,  seldom  exceed  a  dip  of  12  feet  to  the  mile.  The  structure  of  the 
region,  therefore,  has  not  materially  influenced  the  drainage,  and  the 
streams  flow  from  its  surface  as  if  they  were  flowing  from  a  country 
composed  of  unconsolidated  deposits  of  clays,  sands,  and  gravel  hori- 
zontally bedded  throughout. 

TOPOGRAPHIC  HISTORY. 

A  detailed  study  of  the  topographic  features  which  have  been  described 
above  and  of  the  materials  out  of  which  the  land  is  composed  has  re- 
vealed many  of  the  incidents  which  have  produced  the  present  relief. 


62  THE   PHYSIOGRAPHY   OF    CALVERT   COUNTY 

An  outline  of  the  topographic  history  will  now  be  given  under  the  follow- 
ing four  stages,  beginning  with  the  oldest : 

1.  The  Sunderland  Stage. 

2.  The  Wicomico  Stage. 

3.  The  Talbot  Stage. 

4.  The  Eecent  Stage. 

THE  SUNDERLAND  STAGE. 

During  the  Sunderland  stage,  the  oldest  of  the  three  terraces  which 
were  described  above  was  made.  This  terrace  is  known  as  the  Sunder- 
land terrace  and  the  materials  which  compose  it  constitute  the  Sunderland 
formation.  Before  the  Sunderland  stage  was  initiated,  it  is  probable 
that  the  entire  surface  of  Calvert  County  was  covered  with  a  deposit  of 
reddish-brown  clay,  sand,  and  gravel,  which  is  developed  extensively 
over  the  Coastal  Plain  of  Maryland,  Virginia,  the  Carolinas,  and  south- 
ward, and  described  under  the  name  of  the  Lafayette  formation.  As  no 
remnant  of  this  deposit  is  at  the  present  time  known  to  exist  in  Calvert 
County,  it  follows  that  if  it  ever  did  extend  over  this  region,  it  has  since 
been  removed  by  erosion.  It  is  not  necessary  to  discuss  this  question 
further  than  to  say  that  on  the  top  of  Marriott  Hill,  a  short  distance 
beyond  the  northern  border  of  Calvert  County,  an  outlier  of  the  Lafayette 
formation  occurs,  while  around  its  flanks  the  Sunderland  terrace,  with 
its  characteristic  deposits,  is  found  developed.  Both  the  topographic 
and  geologic  relations  of  the  Lafayette  and  Sunderland  formations  in 
this  place  indicate  that  the  hill  existed  as  an  island  whose  shores  were 
washed  by  the  Sunderland  sea  and  around  whose  border  the  Sunderland 
formation  was  deposited.  Again  in  St.  Mary's  County  to  the  southeast 
of  Calvert  County,  an  extensive  mantle  of  Lafayette  was  eroded  by  the 
Sunderland  sea  which  cut  a  scarp-line  against  it  precisely  as  the  waves 
are  now  cutting  a  sea  cliff  against  the  present  shore.  The  Sunderland 
formation  was  laid  down  at  the  base  of  the  scarp-line  by  the  Sunderland 
sea  at  the  same  time  it  was  cutting  back  the  edge  of  the  Lafayette  forma- 
tion and  producing  the  scarp.2 

2  This  subject  will  be  found  discussed  at  length  in  the  Report  on  the 
Pliocene  and  Pleistocene  Deposits  of  Maryland,  Md.  Geol.  Surv.,  1906. 


MARYLAND   GEOLOGICAL    SURVEY  63 

As  the  Sunderland  terrace  within  Calvert  County  is  topographically 
and  geologically  continuous  with  the  Sunderland,  which  in  Anne  Arun- 
del  and  St.  Mary's  counties  surrounds  the  Lafayette,  it  is  probable  that 
the  Lafayette  formation  was  removed  from  the  surface  of  Calvert  County 
in  great  measure  by  the  erosion  and  advance  of  the  Sunderland  sea. 
At  the  time  of  which  we  are  speaking,  Calvert  County  was  considerably 
lower  than  it  is  to-day,  and  little  by  little  as  the  Sunderland  sea  tore 
away  the  edges  of  the  Lafayette  formation  and  gained  on  the  land,  the 
surface  of  Calvert  County  disappeared  beneath  the  water.  This  advance 
of  the  sea  by  erosion  was  also  probably  aided  by  gradual  subsidence.  As 
a  result  of  this  combined  movement,  Calvert  County  was  finally  inun- 
dated by  the  sea  and  its  surface  was  covered  by  a  formation  of  clay,  sand, 
and  gravel  which  is  now  known  as  the  Sunderland  terrace. 

THE  WICOMICO   STAGE. 

After  the  Sunderland  terrace  had  been  deposited,  the  surface  of  Cal- 
vert County  was  once  more  elevated  above  the  surface  of  the  ocean  and 
the  new  land  area  thus  presented  was  immediately  attacked  by  waves  and 
rivers,  and  the  principal  streams  within  Calvert  County,  enumerated 
above,  came  into  existence  and  eroded  extensive  valleys  in  the  surface 
of  the  terrace. 

It  is  probable  that  the  valleys  of  the  Potomac  and  Patuxent  rivers, 
together  with  their  larger  tributaries,  were  cut  during  the  post-Lafay- 
ette uplift  and  that  the  trough  in  which  Chesapeake  Bay  now  lies  was 
also  excavated  by  the  Susquehanna  Eiver  which  flowed  down  from  the 
north  and  out  to  the  ocean  somewhere  in  the  vicinity  of  the  present 
outlet  of  Chesapeake  Bay.  It  is  not  probable  that  at  the  time  of  which 
we  are  speaking  these  depressions  were  cut  to  their  present  depth.  They 
have  apparently  been  deepened  during  each  successive  uplift. 

After  the  Sunderland  terrace  had  been  exposed  for  some  time  to  the 
erosive  work  of  the  elements,  the  surface  was  again  lowered  beneath  the 
water,  but  not  to  the  extent  to  which  it  had  been  during  the  Sunderland 
stage.  The  waters  of  the  Patuxent  River  and  Chesapeake  Bay  advanced 
gradually  up  the  valleys  as  the  land  was  lowered  and  transformed  many 


64  THE   PHYSIOGRAPHY   OF    CALVERT    COUNTY 

of  them  into  estuaries,  covering  the  bottom  of  these  submerged  valleys 
with  deposits  of  sand  and  clay  derived  from  the  adjoining  mainland. 
It  has  been  possible  by  tracing  carefully  these  deposits  to  reproduce  ap- 
proximately the  outline  of  Calvert  County  during  the  Wicomico  stage 
when  the  subsidence  had  reached  its  maximum.  This  is  illustrated  in 
Fig.  2.  By  reference  to  this  figure  it  will  be  seen  that  Hall  Creek  and 
Lyons  Creek  were  transformed  into  estuaries  and  a  peninsula  ran  down 
from  Anne  Arundel  County.  Toward  the  south  the  valleys  of  Fishing 
and  Hunting  creeks  were  completely  occupied  by  an  estuary,  producing 
another  great  tongue  of  land  between  them  and  Hall  Creek,  while  be- 
yond these  a  number  of  islands  existed,  brought  about  by  the  drowning 
of  a  number  of  the  streams,  among  which  Battle  and  Parker  creeks  were 
prominent.  The  Patuxent  Eiver  at  this  time  was  transformed  into  an 
estuary  about  three  times  the  width  of  the  present  one,  appearing  very 
much  as  the  Potomac  Eiver  does  to-day  in  the  lower  portion  of  its  course 
where  it  approaches  Chesapeake  Bay. 

THE   TALBOT   STAGE. 

After  the  region  had  remained  in  this  position  for  a  short  time,  it 
was  raised  again  and  once  more  attacked  by  erosion.  The  various  streams 
which  had  been  converted  into  estuaries  began  once  more  to  vigorously 
attack  the  land  and  to  remove  what  the  waters  of  the  Wicomico  sea  had 
deposited  in  their  valleys,  but  before  this  could  be  accomplished,  the  land 
was  once  more  submerged,  although  not  as  extensively  as  in  either  the 
Sunderland  or  Wicomico  stages.  The  outline  of  Calvert  County,  as  it 
appeared  then,  is  roughly  shown  in  Fig.  3.  It  will  be  seen  that  there  was 
an  approach  to  the  conditions  which  had  existed  during  the  Wicomico 
stage,  as  the  same  river  valleys  were  utilized  again  as  estuaries  during 
the  Talbot  stage,  the  subsidence,  however,  was  not  sufficient  to  cause  a 
complete  drowning  of  the  valleys  and  consequently  the  islands  which 
existed  during  the  Wicomico  stage  were  not  present  during  the  Talbot. 
The  outline  of  Calvert  County  was  nevertheless  extremely  broken  and 
the  Patuxent  Eiver  again  reached  very  nearly  the  dimensions  which  it 
had  during  the  maximum  of  Wicomieo  submergence. 


MARYLAND  GEOLOGICAL  SURVEY. 


CALVERT  COUNTY,  PLATE  III. 


FlG.    I.— VIEW  OF  THE  CALVERT  CLIFFS   NEAR  GOVERNOR  RUN. 


FlG.   2. — VIEW    SHOWING    THE    CHOPTANK    FORMATION    NEAR    THE    MOUTH    OF    ST.    LEONARD 

CREEK. 


MAEYLAND   GEOLOGICAL   SURVEY  65 

THE  RECENT   STAGE. 

Another  elevation  of  the  region  brought  the  Talbot  stage  to  a  close, 
and  the  surface  was  once  more  attacked  vigorously  by  erosion  and  finally 
was  lowered  somewhat  beneath  the  waters  of  the  Patuxent  Biver  and 
Chesapeake  Bay.  It  is  believed  at  the  present  time  that  this  submergence 
is  still  in  progress  and  that  the  land  is  gradually  sinking.  It  is  impos- 
sible to  say  how  much  the  land  was  elevated  at  the  close  of  the  Talbot 
stage,  but  it  is  probable  that  it  stood  much  higher  than  it  does  to-day 
for  mud  and  silt  which  have  been  deposited  since  the  close  of  the  Talbot 
stage  are  now  found  filling  all  the  estuaries  and  creeks,  not  excepting 
the  Patuxent  River.  This  filling  amounts  to  about  50  feet.  During  this 
uplift  the  Susquehanna  River  flowed  the  length  of  Chesapeake  Bay,  re- 
ceiving as  tributaries  all  the  rivers  which  now  drain  the  Coastal  Plain  of 
Maryland  and  Virginia  and  reached  the  ocean  some  miles  beyond  the 
present  shore  line  at  Cape  Henry.  At  the  present  time  the  waves  of 
Chesapeake  Bay  and  of  the  Patuxent  River  are  engaged  in  cutting  against 
the  Talbot  terrace  exactly  as  the  waves  during  the  Talbot  stage  did 
against  the  Wicomico  terrace,  and  the  waves  in  the  Wicomico  stage  did 
against  the  Sunderland  terrace.  A  new  terrace  is,  therefore,  being 
formed  under  the  waves  below  the  Talbot  and  separated  from  it  by  a 
well-defined  scarp-line. 


THE  GEOLOGY  OF  CALVERT  COUNTY 

BY 

GEORGE  BURBANK  SHATTUCK 


INTRODUCTORY. 

Special  attention  is  given  in  the  following  pages  to  the  stratigraphy, 
structure,  and  areal  distribution  of  the  various  deposits  which  are 
found  within  the  borders  of  Calvert  County.  These  deposits 
are  all  un consolidated  except  where  the  local  conditions  have  pro- 
duced unimportant  indurations.  The  deposits  of  Calvert  County  are 
among  the  youngest  deposits  in  Maryland.  They  do  not  date  back 
further  than  the  Eocene  and  extend  with  occasional  breaks  down  to 
the  present.  The  geologic  history  of  Calvert  County  is  complex,  how- 
ever, and  was  frequently  interrupted  by  erosive  intervals,  so  that  por- 
tions of  the  geologic  history  have  been  destroyed  and  lost.  These  breaks 
are  made  manifest  by  the  existing  unconformities  between  the  beds 
of  different  materials. 

The  various  formations  of  Calvert  County  in  their  regular  sequence  of 
superposition  are  as  follows: 

Age.  Formation.  Group. 

fTalbot  1 

Pleistocene J  Wlcomico       L Columbia. 

[Sunderland  J 

rSt.  Mary's 

ink       L Chesapeake. 


[-St.  Mar; 

.J  Choptan 

[Calvert 


Eocene Nanjemoy Pamunkey. 

The  oldest  rocks  of  Calvert  County  are  those  of  the  Eocene,  which  be- 
long to  the  Nanjemoy  formation.  They  do  not  occupy  an  extensive  area,  as 
they  are  present  only  in  the  extreme  northwestern  portion  of  the  county. 
Their  base  is  nowhere  exposed  in  this  region,  but  they  are  believed  to 


68  THE   GEOLOGY   OF    CALVERT    COUNTY 

rest  conformably  on  the  Aquia  formation,  the  basal  member  of  the 
Eocene  in  Maryland. 

Next  above  the  Nanjemoy  are  found  the  three  formations  of  the  Chesa- 
peake Group,  which  are  Miocene  in  age.  They  are,  beginning  with 
the  oldest,  the  Calvert,  Choptank,  and  St.  Mary's  formations.  The  Cal- 
vert  formation  rests  unconformably  on  the  Nanjemoy;  the  Choptank, 
in  turn,  rests  unconformably  on  the  Calvert,  but  passes  into  the  St. 
Mary's  formation  without  a  break.  The  materials  of  the  formations 
which  compose  the  Chesapeake  Group  consist  of  marls,  clays,  diato- 
maceous  earths  and  sands.  Each  formation  is  abundantly  supplied  with 
fossils.  Above  the  St.  Mary's  formation  rests  the  members  of  the 
Columbia  Group,  which  are  Pleistocene  in  age.  These  are,  beginning 
with  the  oldest,  Sunderland,  Wicomico,  and  Talbot.  They  are  all  un- 
conformable  with  whatever  lies  beneath  them  and  they  are  also  uncon- 
formable  with  each  other.  They  are  developed  in  terraces  lying  one 
above  the  other  and  separated  by  well  defined  scarp-lines.  (Fig.  1.) 
The  materials  which  enter  into  them  are  clay,  peat,  sand,  gravel,  and 
ice-borne  boulders.  As  a  group,  they  record  what  took  place  in  Calvert 
County  while  the  regions  to  the  north -were  covered  by  the  great  ice 
sheet. 

THE  EOCENE. 

THE  PAMUNKEY  GROUP. 
THE  NANJEMOY  FORMATION.1 

The  Nanjemoy  formation  is  the  only  representative  of  the  Eocene 
in  Calvert  County.  It  is  extensively  developed  in  other  portions  of 
the  Maryland  Coastal  Plain,  where  it  has  been  carefully  studied,  but 
in  Calvert  County  so  little  of  the  formation  is  present  and  it  dips  so 
rapidly  beneath  tide  that  its  characteristics  are  not  well  defined,  so 
that  what  is  said  in  this  chapter  regarding  it  is  based  largely  on  ex- 
posures which  are  found  in  neighboring  regions. 

'For  a  full  discussion  of  the  Nanjemoy,  the  reader  is  referred  to  the 
Eocene  Report  by  Clark  and  Martin,  published  by  the  Maryland  Geological 
Survey,  1901. 


MARYLAND   GEOLOGICAL    SURVEY  69 

The  name  of  the  formation  was  suggested  by  Nanjemoy  Creek,  in 
Charles  County,  where  it  was  found  to  be  typically  developed.  In 
Calvert  County  the  Nanjemoy  formation  is  exposed  only  in  the  extreme 
northwestern  section,  in  Lyons  Creek  Valley,  and  southward  along  the 
Patuxent  Biver  to  a  point  about  a  mile  below  the  mouth  of  Hall 
Creek.  Throughout  this  region  it  forms  the  basement  rock  of  the 
county,  on  which  the  Calvert  formation  and  the  terraces  of  the  Columbia 
Group  rest.  It  is  so  completely  buried  by  these  over-lying  deposits 
and  their  talus  slopes  that  it  is  seldom  exposed  except  in  the  valleys 
of  streams  where  erosion  is  sufficiently  rapid  to  strip  the  banks  of 
debris.  The  base  of  the  Nanjemoy  formation  is  not  visible  within 
the  borders  of  Calvert  County,  but  if  the  same  relations  hold  here 
as  have  been  observed  elsewhere,  the  Nanjemoy  lies  conformably  on 
the  Aquia  formation,  which  is  the  basal  member  of  the  Eocene  in 
Maryland. 

The  materials  which  make  up  the  deposits  consist  of  marls,  sands 
and  greensands,  which  latter  frequently  become  highly  arenaceous.  Gyp- 
sum crystals  are  also  found  scattered  throughout  the  deposits. 

The  exposure  where  the  Nanjemoy  formation  can  be  seen  in  its 
most  typical  development  is  in  the  cliff  at  Lyons  Creek  Wharf.  The  fol- 
lowing is  a  section  made  at  this  locality  by  Dr.  G.  C.  Martin.2 

Section  on  tank  of  Patuxent  River  one-quarter  mile  below   mouth  of  Lyons   Creek, 
Calvert  County. 

Feet.  Inches. 

Pleistocene.  Sand  and  gravel 6 

Diatomaceous   clay    9 

Neocene.  Miocene.       Sillcious  indurated  stratum  with  Miocene  fossils 10 

Brown   gritty   clay,   with   abundant  casts   of  Miocene 

fossils    4 

Argillaceous  greensand,  with  abundant  casts  of  Nan- 
jemoy fossils    10 

Line    of    concretions 2 

Eocene.     Nanjemoy.     Argillaceous  greensand  and  talus 20 

Total    50  0 

The  thickness  of  the  Nanjemoy  formation  as  calculated  from  neigh- 
boring regions  is  about  125  feet.  The  dip  is  12  to  15  feet  per  mile 
to  the  southeast  and  the  strike  is  from  northeast  to  southwest. 

2  The  Eocene,  Maryland  Geological  Survey,  1901,  p.  72. 


70  THE  GEOLOGY  OF  CALVERT  COUSTTY 

THE  MIOCENE. 
THE  CHESAPEAKE  GROUP. 

The  Miocene  deposits  of  the  Middle  Atlantic  slope  have  been  de- 
scribed under  the  name  of  the  Chesapeake  Group.  In  Maryland,  the 
materials  which  compose  the  formations  of  this  group  consist  of  clay, 
sandy-clay,  sand,  marl  and  diatomaceous  earth.  The  sandy-clay  mem- 
bers are,  when  freshly  exposed,  greenish  to  greenish-blue  but  slowly 
change  under  the  influence  of  the  weather  to  a  slate  or  drab  color. 
As  the  Miocene  beds  contain  but  little  glauconite,  it  is  not  a  difficult 
task  on  the  basis  of  lithologic  criteria  to  separate  them  from  the  Eocene 
deposits,  and  they  are  still  more  readily  distinguished  from  the  Columbia 
loams  and  gravels  above. 

It  has  been  found  possible  to  separate  the  beds  of  the  Chesapeake 
Group  into  three  formations,  which  are  designated,  beginning  with 
the  oldest,  the  Calvert  formation,  the  Choptank  formation  and  the 
St.  Mary's  formation. 

THE   CALVERT   FORMATION. 

Calvert  County  has  suggested  the  name  for  this  formation  because 
of  its  typical  development  there.  In  the  famous  Calvert  Cliffs  along 
the  eastern  border  of  this  county  the  waves  of  Chesapeake  Bay  have 
cut  an  almost  unbroken  exposure  rising  nearly  100  feet  in  height  and 
extending  from  Chesapeake  Beach  to  Drum  Point,  a  distance  of  about 
30  miles. 

Areal  Distribution. 

The  Calvert  formation  which  lies  at  the  base  of  the  Chesapeake  Group 
in  Maryland  crosses  the  state  from  northeast  to  southwest.  On  the 
Eastern  Shore  it  is  found  in  the  southeastern  corner  of  Kent  County, 
throughout  almost  the  entire  extent  of  Queen  Anne's  County  and  the 
northern  portions  of  Talbot  and  Caroline  counties. 

On  the  Western  Shore  the  Calvert  formation  is  found  extensively 
developed  in  Anne  Arundel,  Prince  George's,  Charles,  Calvert,  and  St. 
Mary's  counties.  It  appears  as  a  long  line  of  outcrop  extending  from 
the  hills  near  the  head  of  South  Eiver  estuary  to  a  place  on  the  Calvert 


MARYLAND   GEOLOGICAL    SURVEY  71 

Cliffs  near  Point  of  Eocks.  With  this  breadth,  it  extends  across  south- 
ern Maryland  from  Chesapeake  Bay  to  the  Potomac  River,  and  is  devel- 
oped along  the  latter  stream  from  the  hills  north  of  Washington  to 
the  mouth  of  the  Wicomico. 

Notwithstanding  this  great  development,  the  Calvert  formation  is 
seldom  met  with  on  the  surface  of  the  country  but  must  be  sought  in 
the  cliffs  of  the  larger  estuaries  and  in  the  walls  of  stream  gorges. 
As  on  the  Eastern  Shore  so  on  the  Western,  the  Calvert  formation  is 
covered  by  younger  formations. 

The  distribution  of  the  Calvert  formation  in  this  county  is  shown 
on  the  geologic  map  which  accompanies  this  report.  It  is  found 
throughout  the  entire  northern  two-thirds  of  the  region  from  Lyons 
Creek  to  a  point  two  miles  below  Governor  Run  on  the  Bay  shore  and 
to  the  mouth  of  Ben  Creek  in  the  valley  of  the  Patuxent  River.  Through- 
out this  region  the  Calvert  formation  is  so  extensively  covered  over  by 
the  sands  and  gravels  of  the  formations  belonging  to  the  Columbia 
Group  that  it  is  nowhere  found  along  the  divides,  but  occurs  in  the 
valley  walls  of  every  important  stream.  In  the  northwestern  portion  of 
the  county  it  lies  uncomformably  on  the  eroded  surface  of  the  Nanjemoy 
formation.  This  contact  occurs  at  an  elevation  of  about  20  feet  above 
tide  in  the  valley  of  Lyons  Creek,  but  rapidly  declines  toward  the 
south  until  near  the  mouth  of  Hall  Creek,  the  Nanjemoy  dips  below 
the  level  of  the  Patuxent  River,  and  the  base  of  the  Calvert  formation 
reaches  tide.  From  this  point  southward  to  a  line  drawn  from  the 
mouth  of  Ben  Creek  to  the  Calvert  Cliffs,  midway  between  Governor 
Run  and  Flag  Pond,  the  Calvert  formation  is  found  either  in  the  sides 
or  the  bottom  of  every  creek  valley,  which  is  eroded  to  any  considerable 
depth.  The  headwaters  of  St.  Leonard  Creek  and  a  few  of  its  associates 
on  the  southern  margin  of  the  Calvert  area  have  not  eroded  quite  deep 
enough  to  reach  it.  By  far  the  best  exposure  of  the  Calvert  formation 
is  to  be  seen  along  the  Calvert  Cliffs  from  Chesapeake  Beach  south- 
ward to  two  miles  below  Governor  Run.  Here  there  is  an  exposure  of 
the  Calvert  formation  broken  only  for  a  short  distance  near  Dares 
Wharf,  where  some  of  the  surficial  deposits  cover  over  and  obscure  it. 


72  THE  GEOLOGY  OP  CALVERT  COUNTY 

Strike,  Dip  and  Thickness. 

The  strike  of  the  Calvert  formation  is  in  general  from  northeast 
to  southwest,  but  the  outcrop  frequently  becomes  very  sinuous,  because 
of  erosion  and  changes  in  topography.  Thus  in  the  northern  portion 
of  the  county  streams  have  carved  out  deep  valleys,  producing  a  most 
irregular  outcrop,  which  departs  widely  from  the  direction  of  strike. 

The  dip  is,  as  a  whole,  about  11  feet  to  the  mile  toward  the  south- 
east. Apart  from  the  exposures  on  the  Calvert  Cliffs  of  this  county 
and  the  Nomini  Cliffs  of  Virginia,  there  are  no  good  localities  for 
determining  the  dip,  and  as  it  must  be  calculated  as  a  whole  over 
extensive  regions,  many  of  them  beyond  the  borders  of  the  county, 
slight  changes  which  may  occur  are  not  often  brought  to  light. 

The  Calvert  formation  occupies  the  higher  portions  of  the  stream 
valleys  throughout  the  northern  part  of  the  county  and  gradually 
dips  to  lower  and  lower  levels  as  it  passes  toward  the  southeast  until 
it  sinks'  beneath  tide  level.  The  line  along  which  it  finally  disappears 
in  Calvert  County  extends,  as  indicated  above,  from  the  mouth  of  Ben 
Creek  to  a  point  on  Calvert  Cliffs  midway  between  Governor  Eun 
and  Flag  Pond.  In  the  northern  part  of  the  county,  then,  the  streams 
cut  through  the  basal  members  of  the  formation,  while  in  the  southern 
part  the  deepest  stream  valleys  reach  only  the  upper  members  of  the 
formation,  while  the  shallow  drainage  ways  do  not  cut  low  enough  to 
uncover  it,  but  have  only  sunk  their  valleys  into  the  later  formations  of 
the  Chesapeake  Group. 

The  full  thickness  of  the  Calvert  formation  within  the  borders  of 
the  county  has  nowhere  been  actually  observed.  It  has  been  diagon- 
ally truncated  above  by  the  Choptank  and  younger  forma- 
tions, under  which  it  lies  unconformably  so  that  in  the  region  of 
Davidsonville,  in  Anne  Arundel  County,  it  has  a  thickness  of  about 
50  feet.  From  this  point  it  thickens  rapidly  down  the  dip  until  at 
Crisfield,  in  Somerset  County,  it  shows  a  thickness  of  about  310  feet 
in  an  artesian  well.  From  various  calculations  it  appears  that  the 
average  thickness  in  Calvert  County  is  about  150  feet. 


MARYLAND  GEOLOGICAL  SURVEY. 


CALVERT  COUNTY,  PLATE  IV. 


18 


CHARACTERISTIC  FOSSILS  OF  THE  MIOCENE  FORMATIONS  OF  CALVERT  COUNTY. 


1.  CARCHARIAS  EGERTONI  (Agassiz). 

2.  OLIVA  LITTERATA  Lamarck. 

3.  ECPHORA  QUADRICOSTATA   (Say). 

4.  FULGUR  FUSIFORME  Conrad. 

5.  SURCULA  BISCATENARIA  Conrad. 


7.  TURRITELLA  PLEBEIA  Say. 

8.  MANGILIA  PARVA  (Conrad). 

9.  MACTRA  CLATHRODON  Lea. 
10.  ARCA  STAMINEA  Say. 

i.  ISOCARDIA  M\ UK"':' i  Conrad. 


COLUMBELLA  COMMUNIS  (Conrad).    12.   SPISULA  SUBPONDEROSA  (d'Orb.). 


13.  ASAPHIS  CENTENARIA  (Conrad). 

4.  CHIONE  ALVEATA  (Conrad). 

5.  PECTEN  MADISONIUS  Say. 

6.  VENERICARDIA  GRANULATA  Say. 

7.  SCUTELLA  ABERTI  Conrad  (lateral  vi 

8.  ASTRANGIA  LINEATA  (Conrad). 


MARYLAND    GEOLOGICAL   SURVEY  73 

Character  of  Materials. 

The  materials  composing  the  Calvert  formation  are  as  a  whole  quite 
uniform.  They  consist  of  clay,  marl  and  diatomaceous  earth.  Through- 
out its  entire  extent  the  formation  is  abundantly  supplied  with  fossils. 
The  diatomaceous  earth  is  greenish-blue  when  fresh,  and  weathers  to 
a  light  buff  when  exposed  to  the  air.  It  is  found  in  the  lower 
portions  of  the  formation,  although  diatoms  are  abundant  at  many 
other  horizons.  The  clay  and  marl  are  also  dark  brown  to  bluish-green 
when  fresh  and  change  to  various  tints  of  buff  on  exposure  to  the 
weather.  The  fossils  frequently  are  concentrated  in  great  bands  which 
are  remarkably  constant  throughout  the  formation.  (Plate  II.) 

Stratigraphic  Relations. 

The  Calvert  formation  lies  unconformably  on  the  eroded  edges  of 
the  Nanjemoy.  This  unconformity  is  in  the  nature  of  an  overlap  and 
is  most  easily  seen  along  the  east  bank  of  the  Patuxent  Kiver  in  the 
vicinity  of  Lyons  Creek.  It  may  also  be  seen  in  one  of  the  southern 
tributaries  of  Lyons  Creek,  near  the  place  where  the  highway  leading  to 
Chaney  is  crossed  by  the  Chesapeake  Beach  Eailroad.  In  both  of  these 
localities  a  thin  stratum  of  silicious  sandstone  bearing  fossils  is  clearly 
discernible.  This  lies  in  the  body  of  the  Calvert  formation  and  about 
2  feet  above  its  contact  with  the  underlying  Nanjemoy.  In  the  last 
locality  mentioned  a  waterfall  has  developed  on  this  hard  stratum 
(Plate  I).  Above,  the  Calvert  formation  lies  unconformably  beneath 
the  Choptank  formation. 

Sul-Divisions. 

Within  the  county  borders  the  Calvert  formation  falls  into  two  divi- 
sions which  are  known  as  the  Fairhaven  diatomaceous  earth  and  the 
Plum  Point  marls. 

FAIRHAVEN  DIATOMACEOUS  EARTH. — This  member  lies  at  the  base 
of  the  Calvert  formation  and  is  characterized  by  the  presence  of  a  large 
proportion  of  diatoms  imbedded  in  a  very  finely  divided  quartz  matrix. 
Calcareous  material  is  present  in  this  bed  only  in  very  small  amounts. 


74  THE   GEOLOGY   OF   CALVERT    COUNTY 

Beside  diatoms,  there  are  other  Miocene  fossils,  usually  in  the  form  of 
casts,  and  organic  remains  reworked  from  the  underlying  Eocene  beds. 
Fairhaven,  Anne  Arundel  County,  where  the  beds  are  well  developed, 
has  suggested  the  name  for  this  division. 

The  contact  of  the  diatomaceous  earth  with  the  Eocene  beds  lies 
about  two  feet  beneath  a  band  of  silicious  sandstone  from  4  to  8  inches 
in  thickness,  which  carries  casts  of  Pecten  humphreysii  and  other  Miocene 
fossils.  Above  this  sandstone  is  the  diatomaceous  earth  proper,  which 
is  about  20  feet  in  thickness.  In  the  extensive  pits  at  Lyons  Creek,  where 
the  material  is  being  worked  for  commerce,  the  transition  from  the 
fresh  greenish-blue  to  weathered  buff  color  may  be  seen  in  the  masses 
removed,  progressing  in  concentric  rings.  In  such  specimens,  the  fresh 
greenish  material  is  found  at  the  center  passing  gradually  into  the  buff- 
colored  material  toward  the  periphery. 

The  low  cliffs  which  border  Chesapeake  Bay  south  of  the  pier  at 
Fairhaven  are  composed  of  diatomaceous  earth  with  a  capping  of 
Columbia  gravel.  From  Fairhaven  the  beds  cross  southern  Maryland 
in  a  northeast-southwest  direction  following  the  line  of  strike,  and 
are  worked  at  Lyons  Creek  on  the  Patuxent  and  again  at  Popes  Creek 
on  the  Potomac.  They  may  also  be  found  at  innumerable  places  be- 
tween these  points  in  cuttings  made  by  water-ways.  North  of  this 
diagonal  line,  extending  between  Fairhaven  and  Popes  Creek,  the  diato- 
maceous beds  gradually  rise  until  they  rest  on  the  hilltops,  while  south 
•  of  the  diagonal  line,  they  gradually  disappear  below  tide. 

The  Fairhaven  diatomaceous  earth  has  been  subdivided  into  three 
zones,  which  may  be  characterized  as  follows: 

Zone  1. — At  the  base  of  the  Calvert  formation  and  lying  unconform- 
ably  on  the  Eocene  deposits  is  a  bed  of  brownish  sand  carrying  Phacoides 
(Lucinoma)  contractus.  This  stratum  varies  somewhat  in  thickness 
from  place  to  place,  but  does  not  depart  widely  from  six  feet  on  the 
average. 

Zone  2. — Lying  immediately  above  Zone  1  is  a  thin  stratum  of  white 
sand  of  about  one  foot  in  thickness,  which  is  locally  indurated  to  form 
sandstone.  It  contains  a  large  number  of  fossils,  of  which  the  follow- 


MARYLAND   GEOLOGICAL    SURVEY  75 

ing  are  the  most  important :  Ecphora  tricostata,  Panopea  whitfieldi,  P. 
americana,  Corbula  elevata,  Phacoides  (Ludnoma)  contractus,  Veneri- 
cardia  granulata,  Astarte  cuneiformis,  A.  fhomasi,  TJiracia  conradi,  Pec- 
ten  madisonius,  P.  JiumpJireysii,  Chione  latilirata,  Cytherea  staminea. 

Zone  3. — This  stratum  when  freshly  exposed  consists  of  a  greenish 
colored  diatomaceous  earth  which,  on  weathering,  bleaches  to  a  white 
or  buff-colored  deposit  breaking  with  a  columnar  parting  and  pre- 
senting perpendicular  surfaces.  It  is  very  rich  in  diatomaceous  matter, 
the  mechanical  analyses  of  specimens  yielding  more  than  50  per  cent 
of  diatoms.  The  thickness  of  this  bed  varies  from  place  to  place,  but 
where  it  is  penetrated  at  Chesapeake  Beach  by  an  artesian  well  it  has 
a  thickness  of  about  55  feet.  At  Fairhaven,  where  it  is  well  exposed, 
it  carries  large  numbers  of  Phacoides  (Ludnoma)  contractus.  This 
zone  is  best  exposed  at  Popes  Creek,  Lyons  Creek,  Fairhaven,  and  in 
stream  gullies  lying  along  the  northern  margin  of  the  Miocene  beds. 

PLUM  POINT  MARLS. — The  Plum  Point  marls  occupy  the  remainder 
of  the  Calvert  formation  above  the  Fairhaven  diatomaceous  earth. 
Plum  Point  in  Calvert  County,  where  the  beds  are  typically  developed, 
has  suggested  the  name  for  this  member.  These  marls  consist  of  a 
series  of  sandy-clays  and  marls  in  which  are  imbedded  large  numbers 
of  organic  remains  including  diatoms.  (Plate  II.)  The  color  of  the 
material  is  bluish-green  to  grayish-brown  and  buff.  Fossil  remains  al- 
though abundant  through  the  entire  deposit  are  particularly  numerous  in 
two  prominent  beds  from  30  to  35  feet  apart.  These  beds  vary  in  thick- 
ness from  4£  to  13  feet.  They  may  be  easily  traced  along  the  Calvert 
Cliffs  from  Chesapeake  Beach  to  a  point  2  miles  below  Governor  Eun. 
At  Chesapeake  Beach  they  lie  high  up  in  the  cliffs,  and  pass  gradually 
downward  beneath  the  surface  of  the  water  as  the  formation  is  followed 
southward.  Along  the  Patuxent  Eiver  the  Plum  Point  marls  are  not 
exposed  so  extensively  as  in  the  Calvert  Cliffs  but  they  are  visible 
at  intervals  from  the  cliffs  below  Lower  Marlboro  southward  to  Ben 
Creek. 

When  fresh  the  Plum  Point  marls  and  the  Fairhaven  diatomaceous 
earth  do  not  differ  much  in  appearance.  The  thickness  of  the  former 


76  THE  GEOLOGY  OF  CALVERT  COUNTY 

increases  constantly  down  the  dip  and  it  is  probable  that  the  greater 
portion  of  the  310  feet  assigned  to  the  Calvert  formation  in  the  Crisfield 
well  is  to  be  referred  to  this  member.  The  actual  thickness  of  the  Plum 
Point  marls  within  Calvert  County  is  nowhere  directly  visible,  but  one 
may  gain  a  good  idea  of  its  development  within  the  region  by  comparing 
the  various  sections. 

From  a  detailed  study  of  the  exposures  along  the  Calvert  Cliffs,  it 
has  been  found  possible  to  subdivide  Plum  Point  marls  into  12  zones. 
They  are  characterized  as  follows: 

Zone  4. — At  the  base  of  the  Plum  Point  marls  and  lying  conformably 
on  Zone  3,  the  uppermost  member  of  the  Fairhaven  diatomaceous  earth 
is  a  six-inch  deposit  of  greenish  sandy  clay  carrying  Ostrea  percrassa. 
This  zone  first  makes  its  appearance  along  the  Calvert  Cliffs  at  Chesa- 
peake Beach  and  continues  on  down  the  shore  for  about  2£  miles,  when 
it  can  be  no  longer  distinguished.  Throughout  this  distance,  the  zone 
does  not  dip  toward  the  southeast  in  harmony  with  the  other  zones, 
which  are  visible  above  it,  but  actually  appears  to  rise  slightly  against 
the  dip  until  it  finally  vanishes  at  the  point  indicated.  The  erratic 
behavior  of  this  zone  would  seem  to  indicate  a  local  migration  and 
temporary  occupation  of  this  particular  area  by  Ostrea  percrassa.  This 
zone  corresponds  to  "  Zone  a  "  of  Harris.3 

Zone  5. — This  zone  is  developed  immediately  above  Zone  4  and  at 
Chesapeake  Beach  has  a  thickness  of  7  feet;  as  it  is  followed  southward, 
however,  along  the  Calvert  Cliffs,  it  is  found  to.  thin  rapidly  until  at 
a  distance  of  about  2£  miles  south  of  Chesapeake  Beach  it  has  a  thick- 
ness of  only  2  feet  and  6  inches.  At  this  point  the  base  actually  lies 
higher  than  at  Chesapeake  Beach,  although  on  account  of  the  thinning 
the  top  lies  lower.  From  this  point  southward  it  dips  away  in  har- 
mony with  the  dip  of  the  other  beds  of  the  Calvert  formation.  The 
materials  making  up  this  zone  consist  of  a  greenish  sandy  clay,  which 
carries  scattered  bands  of  Corbula  elevata. 

Zone  6. — This  zone  consists  of  a  greenish  sandy  clay  carrying  large 

"Tertiary  Geology  of  Calvert  Cliffs,  Maryland.  Amer.  Jour.  Sci.,  vol.  xlv, 
1893,  pp.  21-31. 


MARYLAND   GEOLOGICAL    SURVEY  77 

numbers  of  Corbula  eUvata  which  are  distributed  thickly  throughout 
the  stratum  and  not  separated  in  scattered  bands  as  in  the  zones  im- 
mediately below  and  above  it.  At  Chesapeake  Beach,  where  this  zone 
is  best  developed,  it  attains  a  thickness  of  eight  feet,  but  thins  rapidly 
toward  the  south,  like  the  TWO  preceding  zones,  until  at  a  point  2£  miles 
south  of  Chesapeake  Beach  it  has  diminished  to  a  thickness  of  two 
feet.  From  this  place  it  continues  at  about  the  same  thickness  until 
it  finally  disappears  beneath  the  beach  at  Plum  Point. 

Zone  7'. — Lying  immediately  above  the  last  is  a  layer  of  greenish 
sandy  clay,  resembling  very  much  in  appearance  Zone  5,  and  carrying 
scattered  bands  of  Corbula  elevata. 

Zone  8. — This  stratum  is  lithologically  like  those  immediately  pre- 
ceding, but  varies  from  them  in  either  being  devoid  of  fossils  or  in 
carrying  only  a  few  poorly  preserved  fossil  casts  of  a  Corbula,  which  is 
probably  Corbula  elevata.  It  consists  of  a  greenish  sandy  clay  varying 
from  9  to  15  feet  in  thickness.  It  may  be  best  seen  along  the  Calvert 
Cliffs  from  Chesapeake  Beach  to  Plum  Point. 

Zone  9. — This  zone  consists  of  greenish  and  greenish  blue  sandy  clay 
carrying  scattered  layers  of  Corbula  elevata  and  varying  in  thickness 
from  6  feet  at  Chesapeake  Beach  to  2  feet  at  Plum  Point. 

Zone  10. — On  account  of  its  great  and  varied  assemblage  of  fossils 
this  stratum  is  the  most  conspicuous  zone  in  the  entire  Calvert  forma- 
tion. It  consists  of  a  grayish  green  or  a  yellow  to  brown  sandy  clay 
varying  in  thickness  from  6  to  9  feet,  and  is  continuously  exposed 
along  the  Calvert  Cliffs  from  Chesapeake  Beach  till  it  dips  below  tide 
two  or  three  miles  south  of  Plum  Point  Wharf.  The  following  is  a 
partial  list  of  the  fossils  found  in  this  zone :  Turritella  indentata,  PJia- 
coides  anodonta,  Crassalellites  melinus,  Astarte  cuneiformis,  Ostrea 
sellaeformis,  Pecten  madisonius,  Macrocallista  marylandica,  Atrina  har- 
risii,  Area  subrostrata,  Glycymeris  parilis,  etc.  It  corresponds  to  "  Zone 
b  "  of  Harris.4 

Zone  11. — This  stratum  consists  of  a  greenish  blue  to  a  brown  sandy 
clay  changing  locally  to  a  sand.  It  thickens  somewhat  as  it  passes 

4Loc.  cit. 


78  THE   GEOLOGY   OF    CALVERT   COUNTY 

down  the  dip  from  5  feet  where  it  is  exposed  in  the  bluffs  at  Chesa- 
peake Beach  to  13  feet  1£  miles  south  of  Plum  Point  wharf>  where  it 
approaches  tide  level.  It  is  unfossiliferous  or  carries  a  few  imperfect 
fossil  casts. 

Zone  12. — When  typically  developed,  this  zone  consists  of  a  brownish 
sandy  clay,  although  at  times  it  changes  to  a  bluish  color.  In  many  of 
its  exposures  only  imperfect  fossil  casts  can  be  distinguished,  but  in 
other  places  it  is  found  to  carry  Ecphora  quadricostata  var.  umUlicaia, 
Venus  mercenaria,  Cytherea  staminea,  etc.  It  varies  in  thickness  from 
two  to  four  feet  and  corresponds  to  "  Zone  c  "  of  Harris.5 

Zone  13. — The  materials  of  this  zone  consist  of  a  bluish  sandy  clay 
more  or  less  changed  in  sections  to  a  yellowish  or  brownish  color.  It 
carries  imperfect  fossil  casts  and  varies  in  thickness  from  32  feet  at 
Chesapeake  Beach  to  10  feet  at  a  point  one  mile  south  of  Parker  Creek, 
thus  gradually  thinning  as  it  passes  down  the  dip. 

Zone  14. — The  materials  which  make  up  this  stratum  consist  of  a 
brownish  to  yellowish  sandy  clay  abundantly  supplied  with  Isocardia 
fraterna.  It  varies  in  thickness  from  2  to  7  feet  and  corresponds  to 
"Zone  d"  of  Harris.' 

Zone  15. — This  zone  is  the  uppermost  member  of  the  Calvert  forma- 
tion and  consequently  has  been  considerably  eroded  so  that  its  true 
thickness  is  not  definitely  known.  It  consists  of  a  yellowish  sandy  clay 
grading  down  locally  into  yellowish  sand  in  its  lower  portions.  At  a 
point  one  mile  south  of  Plum  Point  Wharf  this  zone  shows  a  greater 
thickness  than  anywhere  else  along  the  Calvert  Cliffs;  at  that  place  it 
measures  48£  feet.  Sections  north  and  south  of  this  point  have  either 
been  in  great  part  replaced  by  Pleistocene  sand  or  have  suffered  by  the 
unconformable  overlapping  of  the  Choptank  formation. 

THE  CHOPTANK  FORMATION. 

The  Choptank  Eiver  has  suggested  the  name  for  this  formation  be- 
cause of  its  great  development  on  the  northern  bank  of  that  estuary  a 
short  distance  below  Dover  Bridge  in  Talbot  County.  In  this  locality 

"Loc.   cit.  "Loc.   cit. 


MARYLAND   GEOLOGICAL    SURVEY  79 

the  Choptank  formation  is  very  fossiliferous,  and  may  be  seen  at  the 
base  of  a  low  cliff  which  borders  the  stream  for  some  distance. 

Areal  Distribution. 

The  Choptank  formation,  which  constitutes  the  second  member  of 
the  Chesapeake  Group  in  Maryland  and  lies  immediately  above  the 
Calvert  formation.,  is  found  in  Caroline,  Talbot,  and  Dorchester  counties, 
on  the  Eastern  Shore,  and  Anne  Arundel,  Calvert,  Prince  George's, 
Charles,  and  St.  Mary's  counties  on  the  Western  Shore.  On  both  the 
Eastern  and  Western  Shores  it  is  very  much  obscured  by  younger  deposits 
which  overlie  it.  In  Calvert  County  the  Choptank  formation  extends 
from  Mt.  Harmony  southward  to  a  line  running  from  Point  of  Rocks 
to  the  mouth  of  Hellen  Creek.  Throughout  the  region  it  lies  uncon- 
formably  on  the  Calvert  formation  and  is  itself  overlaid  conformably 
by  the  St.  Mary's  formation  or  unconformably  by  the  various  formations 
of  the  Columbia  Group.  This  cover  of  surficial  deposits  is  so  extensive 
that  the  Choptank  formation  is  nowhere  exposed  on  the  divides  but 
is  met  with  in  nearly  all  the  stream  valleys  throughout  the  area  desig- 
nated. Near  Mt.  Harmony  the  Choptank  formation  is  found  lying 
on  the  Calvert  at  an  elevation  of  about  100  feet.  From  here  it  sinks 
very  gradually  to  the  vicinity  of  Parker  Creek  and  then  more  rapidly 
till  it  disappears  below  tide  in  the  southern  part  of  the  county.  In 
the  headwaters  of  Fishing  Creek  on  the  east  and  Cocktown  and  Hunting 
Creeks  on  the  west  the  Choptank  formation  lies  high  in  the  valley 
walls  and  the  Calvert  formation  appears  beneath  it.  In  the  southern 
part  of  the  county  in  the  headwaters  of  St.  Leonard  Creek  and  associates 
the  Choptank  formation  occurs  in  the  bottoms  of  the  valleys  and  younger 
formations  lie  above  it.  By  far  the  best  exposures  are  to  be  seen 
along  the  Calvert  Cliffs  from  Parker  Creek  southward  to  Point  of 
Rocks  and  along  the  Patuxent  River  in  the  vicinity  of  St.  Leonard 
Creek. 

Strike,  Dip  and  Thickness. 

The  strike  of  the  Choptank  formation  is  in  general  from  northeast 
to  southwest;  but  because  of  erosion,  particularly  on  the  Western  Shore, 


80  THE   GEOLOGY   OF    CALVERT    COUXTY 

as  pointed  out  above,  the  outcrop  is  very  sinuous  and  the  strike  appears 
to  change  locally. 

The  dip  does  not  appear  to  be  constant  throughout  the  entire  extent 
of  the  formation.  In  Calvert  County,  where  the  Choptank  is  best 
exposed,  the  northern  portion  of  the  formation  down  to  Parkers  Creek 
seems  to  lie  almost  horizontal;  but  south  of  this  point  the  base  of  the 
formation  dips  away  at  about  10  feet  to  the  mile.  Because  of  this 
structure,  the  Choptank  formation  occupies  hilltops  in  the  northern  por- 
tion of  its  area  and  gradually  occupies  lower  and  lower  levels,  until  in 
.the  southern  portion  of  its  area  it  is  found  in  river  bottoms  and  finally 
disappears  beneath  tide.  The  best  place  to  examine  the  dip  of  the 
Choptank  formation  is  along  the  Calvert  Cliffs  between  Parker  Creek 
and  Point  of  Eocks.  Here  an  almost  unbroken  exposure  may  be  seen 
dipping  gradually  toward  the  southeast. 

The  thickness  is  variable.  In  the  Nomini  Cliffs,  Virginia,  it  is 
present  as  a  50-foot  bed  between  the  Calvert  formation  below  and  the 
St.  Mary's  formation  above.  This  is  the  thickest  exposure  which  is 
open  to  direct  observation.  In  the  well  section  at  Crisfield,  mentioned 
above  in  connection  with  the  Calvert  formation,  the  Choptank  forma- 
tion attains  a  thickness  of  about  175  feet.  It  will  thus  be  seen  that 
like  the  Calvert,  it  thickens  as  it  passes  down  the  dip.  The  average 
thickness  in  Calvert  County  appears  to  be  about  100  feet. 

Character  of  Materials. 

The  materials  composing  the  Choptank  formation  are  somewhat  vari- 
able. They  consist  of  fine  yellow  quartz-sand,  bluish-green  sandy- 
clay,  slate-colored  clay  and,  at  times,  ledges  of  indurated  rock.  In 
addition  to  these  materials,  there  are  abundant  fossil  remains  dissemi- 
nated throughout  the  formation.  The  sandy  phase  is  well  shown  in 
the  Calvert  Cliffs  from  Parker  Creek  southward  to  Point  of  Eocks. 
The  sandy-clay  and  clayey  members  may  be  seen  in  the  same  cliffs  near 
Point  of  Eocks  and  southward.  The  indurated  rock  is  well  shown  in 
Drum  Cliff  on  the  Patuxent  and  at  Point  of  Eocks,  and  the  fossil  re- 
mains are  seen  typically  developed  at  Drum  Cliff  and  at  Governor  Eun. 


MARYLAND  GEOLOGICAL  SURVEY. 


CALVERT  COUNTY,   PLATE  V. 


FlG.    I. — VIEW    SHOWING   THE   ST.    MARY'S   FORMATION   AT   COVE   POINT. 


FlG.    2. — VIEW    SHOWING  THE   SUNDERLAND  FORMATION    NEAR   BATTLE   CREEK. 


MARYLAND   GEOLOGICAL   SURVEY  81 

Stratigraphic  Relations. 

The  Choptank  formation  lies  unconformably  on  the  Calvert  forma- 
tion. This  unconformity  is  in  the  nature  of  an  over-lap  but  is  not 
easily  discernible  even  where  the  contact  is  visible.  The  best  place  to 
observe  it  is  in  that  portion  of  the  Calvert  Cliffs  just  below  the  mouth 
of  Parker  Creek.  Even  here,  the  unconformity  cannot  be  seen  while 
standing  on  the  beach  but  may  be  observed  from  a  boat  a  short  distance 
from  the  shore.  The  unconformity  of  the  Choptank  on  the  Calvert 
formation  is  also  proved  from  the  fact  that  at  the  above-mentioned 
locality  the  fossil  bed  which  lies  lowest  in  the  Choptank  formation 
rests  on  the  Calvert,  while  at  Mt.  Harmony  and  northward  the  upper 
fossil  bed  of  the  Choptank  rests  on  the  Calvert  formation.  There  are 
also  certain  differences  between  the  fauna  of  the  Calvert  and  that  of 
the  Choptank.  How  far  this  unconformity  continues  down  the  dip 
after  the  beds  disappear  from  view  is  not  known,  as  the  data  from  well 
records  are  too  meager  to  draw  any  conclusion  regarding  this  question. 
Above,  the  Choptank  formation  lies  conformably  beneath  the  St.  Mary's 
formation. 

Sub-Divisions. 

The  Choptank  formation  has  been  subdivided  into  five  zones  which 
may  be  characterized  as  follows: 

Zone  16. — This  zone  varies  in  composition  from  yellowish  sand  to 
bluish  or  greenish  sandy  clay.  It  is  about  10  feet  thick  and  may  be 
found  exposed  along  the  Calvert  Cliffs  from  near  Parker  Creek  south- 
ward to  a  point  a  little  north  of  Flag  Pond,  where  it  disappears  be- 
neath the  beach.  Where  the  Choptank  first  makes  its  appearance  in 
the  Calvert  Cliffs  at  Parker  Creek  this  zone  is  absent,  and  Zone  17  of 
the  Choptank  rests  immediately  upon  Zone  15  of  the  Calvert.  Zone  1C 
is  for  the  most  part  unfossiliferous,  although  about  3  miles  south  of 
Governor  Kun  a  few  fossils  have  been  discovered  in  it,  of  which  the 
following  are  among  the  number:  Ecphora  quadricostata,  Venus  cam- 
pechiensis  var.  cuneata,  Dosinia  acetcibulum,  Phacoides  contracius,  etc. 

Zone   17. — The   Choptank   formation   carries  two  well-defined  fossil 


82  THE   GEOLOGY   OF    CALVEET    COUNTY 

zones.  Of  these,  Zone  17  is  the  lower  one.  The  material  composing 
this  stratum  is  mostly  yellow  sand  along  the  Calvert  Cliffs.  It  is 
almost  entirely  composed  of  fossils,  the  yellow  sand  simply  filling  in 
the  spaces  between  the  organic  remains.  The  fauna  of  this  zone  is 
extremely  large,  but  the  following  will  suffice  to  give  an  idea  of  some 
of  the  types: 

Ecphora  quadricostata,  Turritella  pleleia,  Panopea  americana, 
Corbula  idonea,  C.  cuneata,  Metis  biplicata,  Macrocattista  marylandica, 
Venus  mercenaria,  V.  campechiensis  var.  cuneata,  Dosinia  acetabulum, 
Isocardia  fraterna,  Cardium  laqueatum,  Crassatellites  turgidulus,  Astarte 
thisphila,  Pecten  coccymdus,  P.  madisonius,  Melina  maxillata,  Area 
staminea,  etc. 

This  zone  makes  its  appearance  along  the  Calvert  Cliffs  at  Parker 
Creek,  where  it  is  about  6  feet  in  thickness,  and  is  continuously  exposed 
until  it  dips  beneath  tide  a  little  north  of  Flag  Pond.  It  may  also 
be  seen  at  various  points  on  the  Patuxent  Eiver.  It  appears  to  thicken 
considerably  southwestward  along  the  strike,  for  where  best  exposed 
on  the  Patuxent  River  it  is  at  least  18  feet  thick  near  the  mouth  of 
St.  Leonard  Creek  and  over  30  feet  thick  at  Drum  Cliff,  in  St.  Mary's 
County.  This  zone  corresponds  to  "  Zone  e  "  of  Harris.7 

Zone  18. — This  zone  is  for  the  most  part  unfossiliferous,  although 
in  places  it  carries  some  imperfect  fossils  and  fossil  casts.  The  mate- 
rial of  which  it  is  composed  is  for  the  most  part  yellowish  sand  above 
but  grades  down  into  bluish  clay  below  and  at  times  the  entire  stratum 
is  composed  of  bluish  clay.  In  thickness  it  varies  from  18  to  22 
feet  along  the  Calvert  Cliffs,  where  it  is  continuously  exposed  from 
Parker  Creek  to  a  point  a  few  miles  south  of  Flag  Pond.  Where  this 
zone  is  exposed  at  Drum  Cliff  it  is  thinned  down  to  about  8  feet  in 
thickness. 

Zone  19. — This  constitutes  the  upper  of  the  two  great  fossiliferous 
zones  of  the  Choptank  formation.  Like  Zone  17  it  is  composed  almost 
entirely  of  fossils  with  the  interstices  filled  with  reddish  and  yellow 
sand.  It  varies  in  thickness  from  12  to  15  feet  along  the  Calvert  Cliffs 

7Loc.   cit. 


MARYLAND   GEOLOGICAL    SURVEY  83 

and  is  continuously  exposed  from  Parker  Creek  southward  to  near  Cove 
Point,  where  the  stratum  dips  beneath  the  beach.  The  following  is 
a  partial  list  of  fossils  found  in  this  zone:  Balanus  concavus,  Corbula 
idonea,  Macrocallista  marylandica,  Dosinia  acetabulum,  Cardium  laquea- 
tum,  PhacO'ides  anodonta,  Crassatellites  marylandicus,  Astarte  thisphila, 
Ostrea  carolinensis,  Pecten  madisonius,  Area  staminea,  etc.  This  zone 
corresponds  to  "  Zone  f  "  of  Harris.8 

Zone  20. — This  zone  lies  at  the  top  of  the  Choptank  formation.  It 
consists  of  greenish  sand  which  is  frequently  oxidized  to  a  red  color, 
and  at  times  it  carries  bands  of  clay.  It  seems  to  be  devoid  of  fossils 
and  is  15  feet  thick,  although  it  has  frequently  suffered  by  erosion.  It 
may  be  best  seen  near  Flag  Pond,  where  it  is  overlaid  by  the  St.  Mary's 
formation. 

THE  ST.  MARY'S  FORMATION. 

The  name  of  this  formation  has  been  suggested  by  St.  Mary's  County 
on  account  of  its  great  development  within  that  region.  The  formation 
is  found  exposed  in  numerous  places  along  the  St.  Mary's  Eiver  in  the 
vicinity  of  St.  Mary's  City.  In  Calvert  County  it  is  best  seen  along 
the  Calvert  Cliffs  from  Point  of  Eocks  southward  to  Drum  Point. 

Areal  Distribution. 

The  St.  Mary's  formation,  like  the  Calvert  and  the  Choptank  forma- 
tions, crosses  the  state  from  northeast  to  southwest.  On  the  Eastern 
Shore,  it  is  present,  if  at  all,  in  Caroline,  Talbot,  Wicomico  and  Dor- 
chester counties. 

On  the  Western  Shore  the  St.  Mary's  formation  is  found  developed 
in  southeastern  Calvert  and  St.  Mary's  counties.  In  this  region 
it  is  very  much  obscured  by  a  mantle  of  younger  material  be- 
longing to  the  Columbia  Group  and  is,  therefore,  seldom  seen  on  the 
surface.  Good  exposures,  however,  are  found  along  the  Bay  shore  and 
the  Patuxent  Eiver  and  its  tributaries.  The  most  extensive  exposure 
is  found  in  Calvert  County  along  the  Bay  shore  from  Point  of  Eocks 

"Loc.   cit. 


84  THE   GEOLOGY   OF    CALVERT    COUNTY 

to  Drum  Point.  Other  exposures  are  found  on  both  banks  of  the 
Patuxent  Eiver  and  along  St.  Johns  Creek  and  Mill  Creek  in  St.  Mary's 
County. 

Strike,  Dip  and  Thickness. 

The  strike  of  the  St.  Mary's  formation,  like  that  of  the  two  preceding 
ones,  is  from  northeast  to  southwest.  On  the  Western  Shore,  because 
of  the  great  diversity  in  the  topography,  the  outcrop  is  extremely  irregu- 
lar and  departs  very  widely  from  the  direction  of  the  strike.  The 
St.  Mary's  formation  rests  conformably  on  the  underlying  Choptank 
and  is  overlain  unconformably  by  younger  materials.  The  dip  averages 
about  10  feet  to  the  mile  toward  the  southeast. 

The  thickness  of  the  St.  Mary's  formation  varies  from  a  few  to  about 
280  feet.  In  the  hilltops  south  of  Prince  Frederick,  where  the  dip 
carries  the  formation  up  to  an  elevation  of  100  feet  or  more,  the 
thickness  thins  down  gradually  to  extinction;  while  in  the  well  boring 
at  Crisfield  it  occupies  a  thickness  of  about  280  feet,  although  it  is  pos- 
sible that  the  upper  portion  of  this  may  be  Pliocene.  The  average 
thickness  of  the  St.  Mary's  formation  in  Calvert  County  appears  to  be 
about  50  feet. 

Character  of  Materials. 

The  materials  composing  the  St.  Mary's  formation  are  clay,  sand, 
and  sandy  clay.  As  exposed  in  this  county,  it  is  typically  a  greenish- 
blue  sandy  clay  bearing  large  quantities  of  fossils  and  resembling  very 
closely  the  sandy  clay  of  the  Calvert  formation  described  above.  Locally, 
the  beds  have  been  indurated  by  the  deposition  of  iron. 

Stratigraphic  Relations. 

The  St.  Mary's  formation  lies  conformably  on  the  Choptank  forma- 
tion. It  is  overlain  unconformably  by  clays,  loams,  sands  and  gravels 
belonging  to  various  members  of  the  Columbia  Group. 


MARYLAND   GEOLOGICAL    SURVEY  85 

Sub-Divisions. 

There  are  certain  faunal  differences  which  separate  it  from  the  Chop- 
tank  formation.  It  has  been  subdivided  into  the  following  zones : 

Zone  21. — This  zone  lies  at  the  base  of  the  St.  Mary's  formation  and 
conformably  on  the  Choptank  formation.  It  consists  of  a  drab  clay 
carrying  sandy  bands  of  about  'the  same  color  and  appears  to  be  devoid 
of  fossils.  It  may  best  be  seen  along  the  cliffs  south  of  Flag  Pond, 
where  it  has  a  thickness  of  about  15  feet. 

Zone  22. — Lying  immediately  above  the  last  mentioned  stratum  is 
another  band  of  drab  clay  in  which  thin  beds  of  fossils  are  developed. 
These  first  made  their  appearance  in  the  cliffs  south  of  Flag  Pond,  and 
although  the  continuity  of  this  bed  is  interrupted  along  the  Bay  shore 
by  talus  slopes  and  overgrowth  of  woodland,  still  it  is  believed  to  be 
continuous  with  the  fossil-bearing  beds  at  the  base  of  the  cliff  at 
Cove  Point.  The  following  are  some  of  the  more  important  fossils 
found  in  this  zone:  Balanus  concavus,  Terebra  inornata,  Mangilia 
parva,  Nassa  peralta,  Columbetta  communis,  Ecphora  quadricostala,  Tur- 
ritella  plebeia,  T.  variabilis,  Polyrdces  Jieros,  Corbula  inequalis,  Peoten 
jeffersonius,  Area  idonea,  etc.  This  stratum  is  about  14  feet  in  thick- 
ness. It  corresponds  to  "  Zone  g  "  of  Harris.9 

Zone  23. — This  zone  is  composed  of  drab  clay  and  sand.  It  has  suf- 
fered considerably  from  erosion,  but  along  the  Calvert  cliffs  it  carries 
some  fossils  of  which  Turrilella  plebeia  is  the  most  important.  It  shows 
a  thickness  of  30  feet,  but  is  unconformably  overlain  by  the  Pleistocene 
sands  and  gravels. 

Zone  24. — A  break  in  the  stratigraphic  continuity  of  the  St.  Mary's 
formation  occurs  south  of  Drum  Point  and  the  exact  relation  of  this 
zone  to  those  preceding  is  not  definitely  known.  It  is  believed,  how- 
ever, to  lie  very  close  to  Zone  23.  At  Chancellor  Point  on  the  St.  Mary's 
River,  where  it  has  been  studied,  15  feet  of  bluish  sandy  clay  are  ex- 
posed, overlain  unconformably  by  Pleistocene  loams.  At  this  place  a 
large  number  of  fossils  are  present,  of  which  the  following  may  be 
mentioned:  Aceteon  ovoides,  Retusa  marylandica,  Terebra  curvilirata, 

"Loc.   cit. 


8G 


THE   GEOLOGY   OF    CALVEET    COUNTY 


Conus  diluvianus,  Surcula  engonata,  Fulgur  fusiforme,  Turritella  varia- 
bilis,  Panopea  goldfussi,  Callocardia  sayana,  Venus  campechiensis  var. 
mortoni,  Isocardia  fraterna,  Phacoides  anodonta,  Pecten  madisonius, 
P.  je-ffersonius,  etc. 

LOCAL  SECTIONS. 

While  instructive  and  important  sections  are  found  in  the  valleys  of 
the  Potomac  and  Patuxent  rivers  and  along  many  of  the  rivers  of  the 
Eastern  Shore,  the  most  complete  section  of  the  Miocene  deposits  along 
the  whole  Atlantic  Coast  occurs  in  the  famous  Calvert  Cliffs  from 
Chesapeake  Beach  southward  to  Drum  Point.  Throughout  this  distance 
the  bluffs  yield  a  complete  sequence  of  the  various  beds  of  the  formations, 
and  the  fossils  are  numerous  and  usually  very  well  preserved.  The 
detailed  description  of  some  of  these  sections  will  now  be  given. 


I.     Section  on  a  southern  branch  of  Lyons  Creek. 

Feet. 

•  White  diatomaceous  clay   (Zone  3) 5 

(3        White     sandstone     containing     following     fossils :       Ecphora 

"E  .2  tricostata,  Panopea  whitfieldi,  P.  americana,  Corbula  elevata, 

Miocene.          >  |  .        Phacoides  contractus,  Venericardia  granulata,  Astarte  cunei- 

5  g  formis,  A.   thomasi,  Thracia  conradi,  Pecten  madisonius,  P. 

fc,  humphreysii,  Chione  latllirata,  Cytherea  staminea   (Zone  2)  .        1 

Brown  sand  containing  Lucina  contracta  (Zone  1) 6 

Eocene.  Greenish   gray   sandy   clay    35 

Total 47 

II.     Section  at  Fairhaven,  one-half  mile  south  of  wharf. 

ijr 

Pleistocene,      o  |  J  Gravel,   sand,   and   clay 10 

*!l 

I  Diatomaceous  sandy  clay  bleached  to  a  whitish  color,  jointed 
so  as  to  have  a  rough  columnar  appearance  carrying  Pha- 
coides contractus  (Zone  3,  in  part) 24 
Diatomaceous  greenish  sandy  clay  breaking  with  conchoidal 
fracture,  carrying  Phacoides  contractus  and  bearing  rolled 
and  reworked  fossils  from  Eocene  in  lower  2%  feet  (Zone  3 
in  part)  36 

Total 


MARYLAND   GEOLOGICAL    SURVEY 


87 


III.     Section  at  Chesapeake  Beach. 

Feet.  Inches. 

C  Yellow  sandy  clay  (Zone  15) 9 

Yellow  sandy  clay  (Zone  14) 5 

Blue  sandy  clay  changing  to  yellowish  brown  sandy 

clay  in  the  upper  12  feet,  fossiliferous  throughout 

upper  portion  (Zone  13)   32 

Greenish     brown     sandy     clay    bearing    fossil     casts 

(Zone  12)    2  6 

Greenish  brown  sandy  clay  (Zone  11) 5 

Grayish   green   sand    containing   some    clay   with    the 

following    fossils :    Turritella    indentata,    Phacoides 

anodonta,   Crassatellites   mellnus,  Astarte  cuneifor- 

mis,  Ostrea  sellceformis,  Pecten  madisonius,  Macro- 

callista    marylandica,    Atrina    harrisii,    Area    sub- 

_  ra          rostrata,  Glycymeris  parilis,  etc.  (Zone  10) 6 

en6'  "    Greenish    sandy    clay    carrying    scattered    layers    of 

Corbula   elevata    (Zone   9) 6 

Greenish    sandy    clay    apparently    devoid    of    fossils 

(Zone    8)     9 

Greenish    sandy    clay    carrying    scattered    layers    of 

Corbula  elevata   (Zone  7) 6 

Greenish     sandy    clay     carrying     large     numbers     of 

Corbula  elevata   (Zone  6) 8 

Greenish  sandy  clay  carrying  Thracia  conradi   (Zone 

5)    7 

Greenish  sandy  clay  carrying  Ostrea  percrassa   (Zone 

4)      G 

Bluish-green     sandy     clay     revealed     in     well-boring 

(Zone  3,  2,  and  1) 62 

Eocene.  Glauconitic  sandy  clay 

Total 97 

IV.     Section  2.5  miles  south  of  Chesapeake  Beach. 

!  o    f  Feet.  Inches. 

Pleistocene.      %  g  J  Yellowish   sandy   loam 7 

*O   9    | 

a  n 

3   r° 
0!  fa     I 

c  Yellow   sandy  clay    (Zone  15) 19 

Fossiliferous  yellowish  sandy  clay  with  an  indurated 
portion  at  top  (Zone  14) 5 

Brownish  and  bluish  sandy  clay  containing  imperfect 
fossil  casts  (Zone  13) 27 

Chocolate  colored  sandy  clay  carrying  imperfect  fos- 
sil casts  (Zone  12) 3 

Unfossiliferous  blue  clayey  sand  (Zone  11) 9 

•£  _o       Fossiliferous  brown  sand  and  clay  (Zone  10) 8 

o  ~   ,  Fossiliferous  bluish  clayey  sand  (Zone  9) 3 

ene.          -.  g  «;  Brownish  sand  and  clay  containing  poorly  preserved 

casts  of  Corbula  (Zone  8) 15 

Brownish    sandy   clay   containing   scattered   bands   of 

Corbula  elevata    (Zone  7) 2  6 

Bluish  clayey  sand  carrying  large  numbers  of  Corbu- 
la elevata   (Zone  6) 2 

Bluish  clayey  sand  carrying  scattered  bands  of  Cor- 
bula elevata   (Zone  5) 2  6 

Bluish  clayey  sand  carrying  Ostrea  percrassa  (Zone  4)  6 

Fossiliferous  bluish  clayey  sand  (Zone  3) 4 


Total 107 


THE   GEOLOGY   OF    CALVERT    COUNTY 
V.     Section  one  mile  north  of  Plum  Point. 


Pleistocene.     !J  "S  -\  Yellowish   sandy   loam.. 

'O  S 

II 


Feet.     Inche 

7 


Yellowish  sandy  clay  (Zone  15) 19 

Yellowish  sand  carrying  Isocardia  fraterna  (Zone  14)        7 

Bluish  and  brownish  sandy  clay  (Zone  13) 25 

Brownish  sand   (Zone  12) 4 

Bluish    clay    grading    downward    into    brown     sand 

(Zone    11)     10 

Yellowish  brown  sandy  clay  bearing  the  following  fos- 
sils :  Siphonalia  devexa,  Ecphora  tricostata,  Turri- 
tella  plebeia,  T.  variabilis.  T.  variabilis  var.  cumber- 
landia,  Polynices  heros,  Corbula  inequalls,  Phacoides 
anodonta,  Crassatellites  melinus,  Astarte  cuneifor- 
mis,  Pecten  madisonius,  Venus  rileyi,  Chione  lati- 
lirata,  Gytherea  staminea,  Melina  maxillata,  Atrina 
harrisii,  Area  subrostrata,  Glycymeris  parllis,  etc., 

(Zone  10)    9 

Bluish    green    clayey    sand    carrying    Corbula    elevata 

(Zone  9)    2 

Bluish  green  clayey  sand  carrying  imperfect  casts  of 

Gorbula  elevata   (  ?)    (Zone  8) 10 

Bluish    green   clayey   sand    containing   large   numbers 

of  Corbula  elevata  (Zone  6) 3 

Bluish  green  clayey  sand  containing  fossil  casts  of 
Corbula  elevata  (Zone  5) 3 


Total 


.    100 


VI.     Section  at  Plum  Point. 


Pleistocene.     £ 


Yellowish  sandy  loam  and  gravel  .  . 


Feet. 
.     14 


Yellowish   sandy  clay  bearing  characteristic  fossils    (Zone   10)  2 

Greenish  sandy  clay  carrying  scattered  layers  of  Corbula  ele- 
vata (Zone  9)  2 

Greenish  blue  clayey  sand  carrying  few  imperfect  fossils 

(Zone  8) 10 

Bluish  clayey  sand  carrying  Corbula  elevata  (Zone  6) 1 


Total 


MARYLAND   GEOLOGICAL    SURVEY 


89 


VII.  Section  one  mile  south  of  Plum  Point  Wharf. 

Feet.     Inches. 

Fossiliferous   yellowish   sandy  clay  grading   into  yel- 
low sand  in  its  lower  portions  (Zone  15) 48  6 

Brownish    sandy    clay    containing   Isocardia    fraterna 

g  (Zone    14)     7 

Miocene  >  "3      Bluish  clay  breaking  with  conchoidal  fracture    (Zone 

rt  g  "        13)      13  6 

Brownish   sandy  clay  carrying  imperfect  fossil  casts 

(Zone  12) 2  6 

Unfossiliferous  bluish  clay  (Zone  11) 11 

Greenish  sand  bearing  characteristic  fossils  (Zone  10)       9 

Total 91  6 

VIII.  Section  1.5  miles  south  of  Plum  Point  Wharf. 

Feet.     Inches. 

Yellowish  sandy  clay  (Zone  15) 19 

Brownish    sandy    clay    containing  Isocardia    fraterna 

(Zone  14)    6 

Bluish  clay   (Zone  13) y 14 

Brownish    sandy   clay   containing  Ecphora   quadricos- 
Miocene  >  *  -<       tata   var-    umoilicata,    Venus   mercenaria,   Cytherea 

I          staminea   (Zone  12) 2  6 

fa      Bluish    clayey    sand    carrying    few    imperfect    fossils 

(Zone  11)    13  6 

Bluish   green   sandy   clay   carrying  "characteristic  fos- 
sils (Zone  10)    6 

Total 61 

IX.     Section  1.5  miles  south  of  Dares  Wharf. 

£.2   f  Feet> 

Pleistocene.     5  |  4  Yellowish  loam,  sand  and  gravel. 30 

S&( 

Bluish  sandy  clay  carrying  Isocardia  fraterna  (Zone  14) 3 

Bluish  clay   (Zone  13) 12 

Miocene.          j»  g  J  Brownish    sandy    clay    carrying    Ecphora    quadricostata    var. 

O  g          umMlicata,  Venus  mercenaria,  Cytherea  staminea  (Zone  12) .  2 

Bluish  clay   (Zone  11) 8 

Total 55 

7 


90 


THE   GEOLOGY   OF    CALVERT    COUNTY 


II 


X.     Section  .5  miles  south  of  Parker  Creek. 


Pleistocene.     |  g  -^  Reddish  sandy  loam   . . . 
I 


Feet.     Inches. 
2 


f  Reddish  sand   (Zone  20) 2 

Reddish    sandy   .clay    containing    Balanus    concavus, 
Corbula  idonea,  Astarte  thisphila,  Pecten  madisonius, 
Venus  campechiensis  var.  cuneata,  Dosinia  acetabula, 
Cardium  laqueatum,  Area  staminea,  etc.,   (Zone  19)      14 
£      Yellowish  sandy  clay  containing  fossil  casts  (Zone  18)     20 

Yellow  sand  containing  Ecphora  quadricostata,  Tur- 
a  n  ritella  plebeia,  Panopea  americana,  Corbula  idonea, 
w  fa  C.  cuneata,  Metis  biplicata,  Macrocallista  mary- 

landica,  Venus  mercenaria,  V.  campechiensis  var. 
cuneata,  Dosinia  acetabula,  Isocardia  fraterna,  Car- 
dium laqueatum,  CrassateHites  turyidulus,  Astarte 
thisphila,  Pecten  coccymelus,  P.  madisonius,  Melina 

maxillata,  Area  staminea,  etc.  (Zone  17) 6 

Miocene. 

Bluish  clay  (Zone  15) 9 

Brownish    sandy    clay    containing    Isocardia    fraterna 

(Zone  14)    4 

Bluish  sandy  clay  (Zone  13) 10 

Brownish  sandy  clay  carrying  Ecphora  quadricostata 
var.      umbilicata,      Venus      mercenaria,      Cytherea 

staminea   (Zone  12) 1  6 

Bluish  clay  (Zone  11) 4 

Total . 73 

XI.     Section  one  mile  south  of  Parker  Creek. 

"J   I  Feet. 

Pleistocene.     1  *  J  Yellow  sand    7 

'  Red  sand  (Zone  20)    2 

^  fl-      Yellow  sand  containing  a  little   clay  and  carrying  character- 

g  2          istic  fossils  (Zone  19) 14 

"a.  5  '   Yellowish    sand    above,    grading    into    bluish    clay    below    and 

6°  H          carrying  bands  of  poorly  preserved  fossils  (Zone  18) 22 
fa       fellow  sand  carrying  characteristic  fossils  (Zone  17) 5 

Yellowish  sand  (Zone  16) 10 

Miocene. 

«  g   f  Bluish  unfossiliferous  clay   (Zone  15) 5 

S  «  J  Bluish  clayey  sand  containing  Isocardia  fraterna  (Zone  14) ...  2 

•5  g   I  Bluish  unfossiliferous  clay  (Zone  13) 10 

u  o   [^Bluish  clay  carrying  characteristic  fossils  (Zone  12) 1 

Total .     78 


MARYLAND   GEOLOGICAL    SURVEY  91 


XII.     Section  at  Governor  Run. 

o  o  r 

~  53  Feet- 

Pleistocene.     |  *  J  Reddish  sandy  loam  ......................................       5 


Reddish  sand   (Zone  20)  ..................................  13 

Yellowish  sandy  clay  carrying  characteristic  fossils   (Zone  19)  12 
Yellowish    sandy    clay    carrying   a    few    poorly    preserved    fos- 

§•  S           sils    (Zone  18)  .........................................  18 

a  g      Yellow  sand  carrying  characteristic  fossils  (Zone  17)  .........  5 

fa   [  Bluish  sandy  clay  (Zone  16)  ...............................  13 

Miocene. 

a   •' 

g  £   I  Bluish  clay  (Zone  15)  ....................................  4 

>  a  -j  Brownish  sandy  clay  carrying  Isocardia  fraterna  (Zone  14)..  4 

a  g      Bluish   clay    (Zone   13)  ...................................  1 

fa    I 

Total  ...............................................  75 

XIII.     Section  2.75  mites  souto  of  Governor  Run. 

*  i  r  Feet- 

Pleistocene.     £  |  J  Reddish  yellow  loam,  sand  and  gravel  .......................  15 


_   o    .  Yellowish  sand  carrying  characteristic  fossils  (Zone  17) 5 

Miocene  «s  +3  J  Greenish  sandy  clay  carrying  Ecphora  quadricostata,  Venus 
campechiensis  var.  cuneata,  Dosinia  acetabula,  Phacoides 
contractus,  etc.  (Zone  16) 

Total 29 

XIV.     Section  at  Flay  Pond. 

13  * 

Pleistocene.     Jj  g  4  Reddish  loam,  sand  and  gravel 40 

I 

'  Drab  clay  and  sand  (Zone  23) 29 

Drab   clay   carrying  scattered  bands   of  fossils  which   contain 
the    following    species :    Balanus    concavus,    Spisula    mary- 
landica,  Callocardia  subnasuta,   Cardium  laqueatum,  Pecten 
madisonius,  Melina  maxillata,  Yoldia  levis,  etc.   (Zone  22)..     14 
Drab  clay  with  sandy  bands  (Zone  21) 15 

Drab  clay  with  sandy  bands  (Zone  20) 15 

Sandy  clay  indurated  above  which  contains  the  following 
species :  Balanus  concavus,  Corbula  idonea,  Macrocallista 
marylandica,  Dosinia  acetabula,  Cardium  laqueatum,  Pha- 
coides anodonta,  Crassatellites  mdrylandicus,  Astarte  this- 
phila,  Ostrea  carolinensis,  Pecten  madisonius,  Area  staminea, 

etc.   (Zone  19) 15 

Bluish  green  sandy  clay  carrying  a  few  fossil  casts  (Zone  18) .     12 
Bluish  green  sandy  clay  carrying  characteristic  fossils    (Zone 
17)    1 

Total ...  141 


92 


THE   GEOLOGY   OF    CALVERT    COUNTY 


XV.     Section  at  Little  Cove  Point. 


Pleistocene.     "5  1  -I  Reddish  and  yellow  loam,  sand  and  gravel . 


Feet. 
.     62 


Bluish  sandy  clay  containing  8  feet  from  base  a  6-inch  layer 

of  fossils  consisting  mostly  of  Turritella  plebeia  (Zone  23)  30 
.«  d  Bluish  sandy  clay  containing  numerous  layers  of  fossils  among 
which  are  the  following  species :  Balanus  concavus,  Terebra 
inornata,  Mangilia  parva,  Nassa  peralta,  Columbella  corn- 
munis,  Ecphora  quadricostata,  Turritella  plebeia,  T.  varia- 
bilis,  Polynices  heros,  Corbula  inequalis,  Pecten  jeffersonius, 
Area  idonea,  etc.  (Zone  22) 17 

Total 


None  of  the  other  drainage  lines  exhibit  as  complete  sections  of  the 
Miocene  as  are  found  along  the  Calvert  Cliffs,  but  occasionally  good  ex- 
posures are  met  with,  one  of  the  more  important  of  which  is  given 
below. 


Section  .25  mile  below  mouth  of  8t.  Leonard  Creek. 


Yellowish  gravel  and  sand. 


reet.   Inches. 
18  6 


f  Greenish  sand  partially  indurated  above,  solidified  to 
I       solid  rock  at  base  of  section   carrying  the  follow- 
ing species :  Balanus  concavus,  Panopea  americana, 
|       Corbula  idonea,   Cardium   laqueatum,  Astarte   this- 
phila,    Pecten    madisonius,    Melina    maxillata,    etc. 
(Zone  17,  in  part) 


Total 


ORIGIN  OF  MATERIALS. 

The  materials  which  compose  the  Miocene  deposits  of  Calvert  County 
may  be  divided  as  regards  their  origin  into  two  classes,  viz.,  the  silicious 
and  arenaceous  materials,  which  are  land-derived,  and  the  calcareous 
materials,  which  are  of  organic  origin.  The  ultimate  source  of  the 
former  was  doubtless  the  rocks  of  the  Piedmont  Plateau  and  regions 
beyond  in  Western  Maryland  and  neighboring  territory, .  but  more  im- 
mediately they  have  been  derived  from  older  coastal  plain  deposits; 
the  one  which  enters  into  the  Miocene  most  conspicuously  being  the 


MARYLAND   GEOLOGICAL    SURVEY  93 

Eocene.  Near  the  contact  of  the  Miocene  and  Eocene,  a  rolled  fauna 
derived  from  the  latter  is  reworked  in  the  former  and  occasionally 
grains  of  glauconite,  which  were  in  all  probability  formed  in  the  Eocene 
occur  in  the  lower  portions  of  the  Miocene. 

The  organic  remains,  which  consist,  for  the  most  part,  of  shells  of 
mollusks  and  bones  of  vertebrates,  are  usually  in  a  very  good  state  of 
preservation.  They  have  been  but  slightly  disturbed  since  deposited 
and  evidently  now  occupy  the  same  relative  positions  which  they  did  at 
the  time  when  they  lived. 

THE  PLEISTOCENE. 
THE  COLUMBIA  GROUP. 

The  Columbia  Group  is  the  name  applied  to  a  series  of  beds  of  clay, 
loam,  sand,  gravel,  and  ice-borne  boulders,  which  are  stratigraphically 


FIG.  1. — Diagram  showing  ideal  arrangement  of  the  various  terrace  forma- 
tions in  the  Maryland  Coastal  Plain. 

younger  and  lie  topographically  below  the  Lafayette  formation.  They  are 
widely  distributed  over  the  surface  of  the  Coastal  Plain  from  Atlantic 
Highlands  southward  to  Mexico  and  are  Pleistocene  in  age,  being  the  last 
formations  which  have  been  laid  down  in  the  region  before  the  Eecent 
deposits  were  formed.  The  formations  which  constitute  the  Columbia 
Group  are,  beginning  with  the  oldest,  the  Sunderland,  Wicomico,  and 
Talbot.  These  deposits  were  laid  down  for  the  most  part  during  the 
glacial  period,  but  a  definite  correlation  of  them  with  the  glacial  deposits 
of  New  Jersey  and  other  regions  is  not  practicable  in  the  present  state 
of  knowledge.  When  the  field  relations  which  exist  between  these  two 
great  classes  of  deposits  are  more  accurately  known,  a  correlation  will, 
no  doubt,  be  possible.  The  various  formations  of  the  Columbia  Group 


94  THE   GEOLOGY   OF    CALVEET    COUNTY 

lie  unconformably  on  whatever  rocks  are  beneath  them.  The  clay,  peat, 
loam,  sand,  gravel,  and  ice-borne  boulders,  out  of  which  they  are  com- 
posed, occur  in  irregular  beds  or  are  developed  in  lenses.  They  are 
mixed  together  in  varying  amounts  and  grade  over  into  each  other  both 
horizontally  and  vertically.  Two  of  the  formations,  the  Sunderland  and 
Talbot,  carry  determinable  vegetable  remains,  and  the  latter  has  yielded 
in  addition  fragments  of  fossil  insects.  The  various  members  of  the 
Columbia  are  developed  in  terraces  lying  one  above  the  other  in  order 
of  their  age,  the  oldest  occupying  topographically  the  highest  position 
(Fig.  1).  They  all  dip  gently  toward  the  surrounding  waters  and  to- 
gether are  widely  distributed  over  the  surface  of  the  county  and  obscure 
in  a  great  measure  the  older  deposits  which  lie  beneath  them. 

THE  SUNDERLAND  FORMATION. 

The  Sunderland  formation  has  been  named  from  its  typical  develop- 
ment near  the  hamlet  of  Sunderland  in  Calvert  County.  It  consists  of 
a  wave-built  terrace,  which  was  formed  by  the  waters  of  the  Atlantic 
Ocean  or  its  estuaries  when  the  country  stood  at  a  lower  level  than  to-day. 
It  is  distributed  over  the  entire  county  occupying  the  divides  between 
the  headwaters  of  the  principal  streams.  Since  the  time  of  deposition, 
the  Sunderland  formation  has  suffered  extensively  from  erosion.  Water- 
ways have  opened  up  their  valleys  through  it  and  have  transformed  a 
once  continuous  mantle  of  loam  and  gravel  into  a  series  of  isolated 
patches  with  sinuous  outlines  occupying  the  higher  portions  of  the 
county,  and  its  once  level  surface  has  now  been  changed  by  the  same 
processes  into  a  gently  rolling  upland. 

Areal  Distribution. 

The  Sunderland  formation  is  the  most  widely  developed  of  the  Pleis- 
tocene deposits  in  Calvert  County.  It  occupies  the  highest  divides  from 
the  northern  margin  of  the  region  at  Lyons  Creek  southward  to  the 
vicinity  of  Drum  Point.  Along  the  western  border  of  the  county  in  the 
valley  of  the  Patuxent  Eiver,  as  well  as  in  many  of  the  streams  which 
penetrate  it,  the  Sunderland  is  surrounded  by  the  younger  formations 


MARYLAND   GEOLOGICAL    SURVEY  95 

of  the  Columbia  Group  which  are  deposited  in  terraces  at  a  lower  level. 
On  the  eastern  margin  of  the  county  these  lower  formations  have  in  a 
large  measure  been  removed  by  erosion  so  that  the  Sunderland  stands 
out  prominently  and  frequently  may  be  seen  occupying  the  uppermost 
stratum  of  the  cliffs,  overlying  unconformably  the  older  deposits  of 
Miocene  beneath. 

Many  streams  have  forced  their  headwaters  back  into  the  body  of  the 
Sunderland  formation  so  that  it  no  longer  is  as  continuous  as  when 
first  deposited,  but  has  developed  a  sinuous  outline  and  is  broken  up  into 
a  number  of  isolated  areas  (Plate  VII,  Fig.  1).  The  most  important  of 
these  areas  extends  from  Lyons  Creek  southward  to  the  Fishing-Hunting 
Creek  depressions.  Another  one  extends  from  this  point  southward  to  the 
Parker-Battle  Creek  valleys,  and  a  third  from  this  depression  southward 
to  Cove  Point,  although  it  is  almost  severed  by  the  headwaters  of  St. 
Leonard  Creek  opposite  Flag  Pond.  These  areas  stood  out  as  islands 
when  the  country  was  submerged  during  Wicomico  time  (Fig.  2  and 
Geological  map). 

Structure  and   Thickness. 

In  the  northern  portion  of  Calvert  County  the  base  of  the  Sunderland 
formation  lies  at  an  elevation  of  about  90  feet,  and  in  the  southern  por- 
tion at  about  70  feet,  indicating  a  difference  between  the  two  localities 
of  20  feet  in  32  miles,  or  a  dip  of  .7  of  a  foot  per  mile  toward  the  south- 
east. The  highest  point  of  the  surface  of  the  Sunderland  formation  is 
near  Mt.  Harmony  in  the  northern  part  of  the  county,  where  the  eleva- 
tion reached  is  about  180  feet.  Farther  south,  near  the  mouth  of  the 
Patuxent  Eiver,  the  surface  of  the  Sunderland  does  not  exceed  127  feet, 
and  where  it  finally  disappears,  near  Drum  Point,  it  is  about  90  feet 
in  height.  This  slope  of  the  surface  is  probably  due  not  only  to  a  slight 
dip  of  the  formation  toward  the  southeast,  but  also  to  the  initial  slope 
which  was  imparted  to  the  formation  while  it  was  being  deposited  as  a 
terrace  beneath  the  waves  of  the  Sunderland  sea.  Beside  the  slope  to- 
ward the  southeast  there  is  also  a  gentle  decline  from  the  water-shed 
which  passes  down  the  backbone  of  the  county  to  the  Patuxent  Eiver 


96  THE  GEOLOGY  OF  CALVERT  COUNTY 

on  one  side  and  to  Chesapeake  Bay  on  the  other.  The  most  pronounced 
slope  is  toward  the  former  as  much  of  the  Sunderland  formation  has 
been  eroded  from  the  latter. 

The  thickness  of  the  Sunderland  formation  is  extremely  variable. 
About  a  mile  south  of  Little  Cove  Point,  near  the  mouth  of  the  Patuxent 
Kiver,  a  thickness  of  85  feet  has  been  measured,  which  is  the  greatest 
anywhere  visible  throughout  the  county.  From  this  it  thins  down  and 
disappears.  Its  average  thickness  for  the  region  is  very  close  to  35  feet. 

Character  of  Materials. 

The  materials  which  compose  the  Sunderland  formation  consist  of 
clay,  loam,  peat,  sand,  gravel,  and  ice-borne  boulders.  These,  as  a  rule, 
do  not  lie  in  well-defined  beds,  but  grade  into  each  other  both  vertically 
and  horizontally.  The  coarser  materials,  with  the  exception  of  ice-borne 
boulders,  are  usually  found  with  a  cross-bedded  structure,  while  the 
clays  and  finer  materials  are  either  developed  in  lenses  or  are  horizontally 
stratified.  The  ice-borne  blocks  are  scattered  through  the  formation 
and  may  occur  in  the  gravel  beneath  or  in  the  loam  above.  There  is 
distinguishable  throughout  the  formation  a  tendency  for  the  coarser 
materials  to  occupy  the  lower  portions  and  the  finer  the  upper  portions 
of  the  formation,  but  the  transition  from  one  to  the  other  is  not  marked 
by  an  abrupt  change.  The  coarser  materials  are  frequently  found  above 
in  the  loam  and  the  finer  materials  below  in  the  gravel.  Many  of  these 
materials  are  in  an  advanced  stage  of  decay.  A  fossil  bed  bearing  car- 
bonaceous matter  containing  recognizable  plant  remains  occurs  at  Point 
of  Eocks. 

Stratigraphic  Relations. 

The  Sunderland  formation  is  built  as  a  terrace  lying  unconformably 
and  somewhat  irregularly  on  the  older  deposits  of  Eocene  and  Miocene 
age.  This  terrace  was  laid  down  about  the  margin  of  the  Lafayette 
formation  although  this  relation,  so  well  shown  in  adjacent  regions,  is 
not  represented  in  this  county.  At  Charlotte  Hall,  in  St.  Mary's  County, 
and  at  Marriott  Hill,  in  Anne  Arundel  County,  the  surface  of  the  Lafay- 


MARYLAND  GEOLOGICAL  SURVEY. 


CALVERT  COUNTY,   PLATE  VI. 


20 


CHARACTERISTIC   FOSSIL   PLANTS   FROM    THE  PLEISTOCENE  OF  CALVERT  COUNTY. 


1-6.  QUERCUS  PSEUDO-ALBA  Hollick. 
7,  8.   ACER  SP.  ?  Hollick. 

9.  CELTIS  PSEUDO-CRASSI  FOLIA  Hollick. 

10.  CARPINCS  PSEUDO-CAROLINIANA  Hollick. 
1-13.  ULMUS  PSEUDO-RACEMOSA  Hollick. 


14,  15.  PLANERA  UNGERI  Ett. 

1 6,  17.  SEQUOIA  ANGUSTI  FOLIA  Lesq. 

15,  ig.  BUMELIA  PSEUDO-LANUGINOSA  Hollick. 

20.  CASSIA  SP.  ?   Hollick. 


MARYLAND   GEOLOGICAL    SURVEY  97 

ette  and  that  of  the  Sunderland  are  separated  by  a  scarp  similar  in  its 
form  and  origin  to  those  which  separate  the  other  terrace  formation  of 
the  Coastal  Plain. 

In  almost  every  place  where  good  sections  of  Pleistocene  materials  are 
exposed  the  deposit  from  base  to  top  seems  to  be  a  unit.  In  other  places, 
however,  certain  layers  or  beds  are  sharply  separated  from  underlying 
beds  by  uneven  lines  similar  to  the  irregular  lines  of  a  cross-bedded  de- 
posit. These  breaks  disappear  in  short  distances,  showing  clearly  that 
they  are  only  local  phenomena  within  the  same  formation  produced  by 
the  contemporaneous  erosion  of  shifting  shallow-water  currents,  and  in 
closely  adjoining  regions  they  seem  to  have  no  relation  to  each  other.. 
Since  the  Pleistocene  formations  occupy  so  nearly  a  horizontal  position 
it  would  be  possible  to  connect  these  separation  lines  if  they  were  sub- 
aerial  erosional  unconformities.  In  the  absence  of  any  definite  evidence 
showing  these  lines  to  be  stratigraphic  breaks  separating  two  formations, 
they  have  been  disregarded.  Yet  it  is  not  improbable  that  in  some  places 
the  waves  of  the  advancing  sea  in  Sunderland,  Wicomico,  and  Talbot 
times  did  not  entirely  remove  the  beds  of  the  preceding  period  of  deposi- 
tion over  the  area  covered  by  the  sea  in  its  next  transgression.  Especially 
would  deposits  laid  down  in  depressions  be  likely  to  persist  as  isolated 
remnants  which  later  were  covered  by  the -next  mantle  of  Pleistocene  ma- 
terials. If  this  is  the  case  each  formation  from  the  Lafayette  to  the 
Wicomico  is  probably  represented  by  fragmentary  deposits  beneath  the 
succeeding  Pleistocene  formations.  Thus  in  certain  sections  the  lower 
portions  may  represent  an  earlier  period  of  deposition  than  that  of  the 
overlying  beds.  In  those  regions  where  older  materials  are  not  exposed 
in  the  base  of  the  escarpments  each  Pleistocene  formation  near  its  inner 
margin  probably  rests  upon  the  attenuated  edges  of  the  next  older  forma- 
tion. Since  lithologic  differences  furnish  insufficient  criteria  for  the 
separation  of  these  late  deposits  and  sections  are  not  numerous  enough 
to  distinguish  between  local  inter-formational  unconformities  and  wide- 
spread unconformities  resulting  from  an  erosion  interval,  the  whole 
mantle  of  Pleistocene  materials  occurring  at  any  one  point  is  referred 
to  the  same  formation.  The  Sunderland  is  described  as  overlying  the 


98 


THE    GEOLOGY   OF    CALVERT    COUNTY 


Jurassic  (?),  Cretaceous,  Eocene,  and  Miocene  deposits  and  extending 
from  the  base  of  the  Lafayette-Sunderland  escarpment  to  the  base  of  the 
Sunderland-Wicomico  escarpment.  The  few  deposits  of  Lafayette  ma- 
terials which  may  possibly  underlie  the  Sunderland  are  disregarded  be- 
cause unrecognizable.  Similarly  the  Wicomico  is  described  as  including 
all  the  gravels,  sands,  and  clays  overlying  the  pre-Lafayette  deposits 
and  extending  from  the  base  of  the  Sunderland-Wicomico  escarpment  to 
the  base  of  the  Wicomico-Talbot  escarpment.  Perhaps,  however,  ma- 
terials of  later  age  may  occasionally  rest  upon  remnants  of  the  Lafayette 
and  Sunderland  formations,  and  the  same  is  true  of  the  Talbot  formation. 

Local  Sections. 

The  materials  which  compose  the  Sunderland  formation  vary  rapidly 
from  place  to  place.  The  following  sections,  however,  will  give  an  idea 
of  the  character  of  the  formation: 


Section  on  Bay  Shore  two  miles  south  of  Cove  Point. 

Feet.     Inches. 

'  Sandy  loam 3 

Sand  and  gravel 20 

Iron  layer    3 

Pine  white  and  red  sand 3  6 

Drab  clayey  sand 1 

Reddish   sand    6 

Pleistocene.     ,g  0  -I  Brab   clayey   sand 1 

Fine  white  and  red  sand 3  G 

Drab  clay    8 

Fine  sand    6 

Drab  clay    3 

Red  sand 2  0 

Iron  layer   2 

bll 
Miocene.  |  |   I  Possiliferous  sandy  clay 54 

ill   I 

Total 96  7 

Section  on  Bay  Shore  near  Flag  Pond. 

1  |   \  Feet. 

Pleistocene,     g  |  J  Reddish  sandy  clay  and  cross-bedded  sand  and  gravel 40 

111 


MARYLAND   GEOLOGICAL    SURVEY  99 


Feet. 
Drab-colored  sandy  clay  bearing  fossils 66 


Iff 

a  a "{  Drab-colored  sandy  clay  bearing  fossils 74 

Total 180 

THE   WICOMICO    FORMATION. 

The  next  younger  formation  of  the  Columbia  Group  is  the  Wicomico. 
It  has  received  its  name  from  the  Wicomico  River  in  Charles  and  St. 
Mary's  counties,  for  in  the  valley  of  this  estuary  it  is  found  well  de- 
veloped. Like  the  Sunderland,  it  consists  of  clay,  loam,  sand,  gravel, 
and  ice-borne  boulders  which  were  deposited  by  the  waters  of  Chesapeake 
Bay  and  its  estuaries.  Since  its  deposition  it  has  suffered  considerably 
from  erosion. 

Areal  Distribution. 

The  Wicomico  formation  is  not  as  extensively  developed  in  Calvert 
County  as  its  predecessor,  the  Sunderland.  It  occupies  a  lower  level 
and  wraps  about  the  latter  like  a  border,  not  only  along  the  margin  of 
the  Patuxent  River,  but  in  all  the  valleys  of  the  principal  streams  which 
penetrate  the  body  of  the  Sunderland  formation.  Along  the  Bay  shore 
the  Wicomico  has  been  largely  removed,  but  fragments  of  it  are  still  to 
be  found  in  the  vicinity  of  Chesapeake  Beach,  Plum  Point,  Dares  Wharf, 
Flag  Pond,  and  Cove  Point.  In  the  valleys  of  Fishing  and  Hunting 
creeks  the  Wicomico  formation  extends  across  the  county  from  Chesa- 
peake Bay  to  the  Patuxent  River.  Farther  south,  in  the  Parker-Battle 
creek  valleys,  a  similar  continuous  deposit  of  Wicomico  existed  although 
it  has  been  almost  entirely  removed  from  the  valley  of  the  former.  In 
the  valley  of  St.  Leonard  Creek  the  Wicomico  formation  extends  well 
back  toward  the  shore  of  Chesapeake  Bay,  but  does  not  extend  entirely 
across  the  divide  as  it  is  separated  by  a  narrow  neck  of  Sunderland. 


100  THE   GEOLOGY   OF    CALVERT    COUNTY 

Many  streams  have  forced  their  headwaters  back  into  the  body  of 
the  Wicomico  formation  so  that  it  no  longer  is  as  continuous  as  when 
first  deposited,  but  has  developed  a  sinuous  outline  and  is  broken  into  a 
number  of  isolated  areas. 

Structure  and  Thickness. 

The  base  of  the  Wicomico  formation  throughout  the  county  rests  at 
an  elevation  of  about  40  or  45  feet  and  has  suffered  apparently  little  or 
no  deformation  since  it  was  deposited.  There  is,  however,  a  gentle  slope 
from  the  inner  margin  to  its  outer  edge  where  it  approaches  the  sur- 
rounding waters.  This  is  not  to  be  attributed  to  a  tilting  of  the  forma- 
tion, but  is  due  to  the  original  slope  which  the  formation  had  when  it 
was  deposited. 

The  thickness  of  the  Wicomico  formation  is  extremely  variable.  Near 
Dares  wharf  a  thickness  of  38  feet  has  been  measured.  In  other  places, 
however,  the  formation  has  been  found  to  thin  down  and  disappear. 
Its  average  thickness  for  the  county  is  about  20  feet. 

Character  of  Materials. 

The  materials  which  compose  the  Wicomico  formation  consist  of 
clay,  loam,  sand,  gravel,  and  ice-borne  boulders.  These,  as  a  rule,  do 
not  lie  in  well-defined  beds,  but  grade  into  each  other  both  vertically 
and  horizontally.  The  coarser  materials,  with  the  exception  of  ice- 
.  borne  boulders,  are  usually  found  with  a  cross-bedded  structure,  while 
the  clays  and  finer  materials  are  either  developed  in  lenses  or  are  hori- 
zontally stratified.  The  ice-borne  blocks  are  scattered  throughout  the 
formation  and  may  occur  in  the  gravel  beneath  or  in  the  loam  above. 
There  is  distinguishable  throughout  a  tendency  for  the  coarser  materials 
to  occupy  the  lower  portions  and  the  finer  materials  the  upper  portions 
of  the  formation,  but  the  transition  from  the  one  to  the  other  is  not 
marked  by  an  abrupt  change.  The  coarser  materials  are  frequently 
found  above  in  the  loam  and  finer  materials  below  in  the  gravel,  and  are 
frequently  much  decayed. 


MARYLAND   GEOLOGICAL    SURVEY  101 

Stratigraphic  Relations. 

The  Wicomico  formation  is  deposited  as  a  terrace  lying  unconformably 
and  somewhat  irregularly  on  the  older  beds  of  Eocene  and  Miocene  age. 
This  terrace  was  laid  down  about  the  margin  of  the  Sunderland  forma- 
tion and  locally  is  believed  to  lap  tip  on  the  thin  eroded  edges  of  the  lat- 
ter, which  are  supposed  to  run  out  a  short  distance  beneath  it.  It  is 
everywhere  separated  from  the  Sunderland  formation  by  a  well-defined 
scarp,  which  is  an  ancient  cliff  cut  by  the  waves  of  the  Wicomico  sea 
during  the  post-Sunderland  depression  (Plate  VII,  Fig.  2). 

Local  Sections. 

The  materials  which  compose  the  Wicomico  formation  vary  rapidly 
from  place  to  place.  The  following  sections,  however,  will  give  an  idea 
of  the  character  of  the  formation : 

Section  on  Bay  Shore  one  mile  north  of  Dares  Wharf. 

oaf  Feet.  Inches. 

"g  33  J  Reddish  yellow  cross-bedded  sand  and  gravel 36 


Miocene.  £  "3  J  Greenish  sandy  clay   . 

fa  Total... 


Section  on  Patuxent  River  at  Hollin  Cliff. 


Feet 

:   7 


Miocene.  {£  «  J  Fossiliferous  sandy  clay  ..................................     63 

^   *•          Total  ...............................................     73 

THE  TALBOT  FORMATION. 

The  Talbot  formation  has  been  named  from  Talbot  County,  Maryland, 
where  it  is  extensively  developed.     In  Calvert  County  it  consists  of  a 


LIBRARY 

UNIWRRTTY  OF  CALIFORNIA 
SANTA  BARBARA 


]Q2  THE   GEOLOGY   OF    CALVEET    COUNTY 

wave-built  terrace  composed  of  clay,  loam,  peat,  sand,  gravel,  and  ice- 
borne  boulders,  which  have  been  deposited  by  the  waves  of  Chesapeake 
Bay  and  its  estuaries.  The  surface  of  the  Talbot  formation  is  coinci- 
dent with  the  lowest  of  the  terrace  surfaces  described  above.  Since  its 
deposition  it  has  suffered  less  from  erosion  than  either  the  Sunderland 
or  Wicomico  formations. 

Areal  Distribution. 

The  Talbot  formation  is  developed  as  a  fringe  about  the  margin  of  the 
Wicomico  and  occupies  the  lowest  level  of  the  three  terraces.  In  the 
valley  of  the  Patuxent  River,  as  well  in  the  depressions  of  its  principal 
tributaries,  the  Talbot  formation  is  found  well  developed,  but  on  the 
Bay  shore  it  seems  to  have  suffered  considerably  from  erosion  and  is 
absent  along  much  of  the  coast  line.  It  may  be  seen,  however,  near 
Chesapeake  Beach,  Dares  Wharf,  Cove  Point,  and  Drum  Point.  In  these 
localities  it  seems  to  have  been  deposited  near  the  headwaters  of  former 
valleys,  the  lower  portions  of  which  have  been  removed  by  erosion. 

A  large  number  of  streams  have  started  to  sink  gullies  in  the  body  of 
the  Talbot  formation,  but  as  yet  have  not  developed  extensive  drainage 
systems  and  the  continuity  of  the  deposit  has  been,  therefore,  little 
affected  by  them. 

Structure  and  Thickness. 

The  base  of  the  Talbot  formation  ranges  in  elevation  from  a  few  feet 
above,  to  a  few  feet  below  tide.  There  seems  to  be  no  general  rule  for 
this  variation  and  it  is  apparently  due  to  deposition  on  a  slightly  uneven 
surface.  The  highest  portions  of  the  surface  of  the  Talbot  formation 
are  found  around  the  margin  where  it  abuts  against  the  Wicomico  for- 
mation. Here  at  the  base  of  the  Talbot-Wicomico  scarp  it  has  an  alti- 
tude of  about  40  to  45  feet  and  slopes  away  gently  toward  the  surround- 
ing waters.  This  is  not  to  be  attributed  to  a  tilting  of  the  formation, 
but  is  due  to  the  original  attitude  which  the  formation  had  when  it  was 
deposited. 

The  thickness  of  the  Talbot  formation  is  variable.     Near  Dares  Wharf 


MARYLAND   GEOLOGICAL    SURVEY  103 

a  thickness  of  33  feet  has  been  observed.  In  other  places  the  formation 
has  been  found  to  thin  down  and  disappear.  Its  average  thickness  for 
the  county  is  about  15  feet. 

Character  of  Materials. 

The  materials  which  compose  the  Talbot  formation  consist  of  clay, 
loam,  peat,  sand,  gravel,  and  ice-borne  boulders.  These,  as  a  rule,  do 
not  lie  in  well-defined  beds,  but  grade  into  each  other  both  vertically  and 
horizontally.  The  coarser  materials,  with  the  exception  of  ice-borne 
boulders,  are  usually  found  with  a  cross-bedded  structure,  while  the 
clays  and  finer  materials  are  either  developed  in  lenses  or  are  horizontally 
stratified.  The  ice-borne  blocks  are  scattered  throughout  the  formation 
and  may  occur  in  the  gravel  beneath  or  in  the  loam  above.  There  is 
distinguishable  throughout  a  tendency  for  the  coarser  materials  to  occupy 
the  lower  portions  and  the  finer  the  upper  portions  of  the  formation, 
but  the  transition  from  one  to  the  other  is  not  marked  by  an  abrupt 
change.  The  coarser  materials  are  frequently  found  above  in  the  loam 
and  finer  materials  below  in  the  gravel.  They  also  show  less  decay  than 
in  the  other  surficial  formations.  Within  the  Talbot  formation  there 
are  a  number  of  lenses  of  drab  clay,  bearing  plant  remains.  The  most 
important  of  these  are  situated  one  mile  north  of  Drum  Point  on  the 
shore  of  the  Patuxent  Eiver,  about  a  mile  below  the  mouth  of  St.  Leon- 
ard Creek.  These  have  been  discussed  at  length  in  the  succeeding 
chapter.  They  will,  therefore,  not  be  considered  here  except  to  say  that 
the  locality  north  of  Drum  Point  yields,  in  addition  to  vegetable  re- 
mains, fragments  of  fossil  insects. 

Stratigraphic  Relations. 

The  Talbot  formation  is  deposited  as  a  terrace  lying  unconformably 
and  somewhat  irregularly  on  the  older  beds  of  Eocene  and  Miocene  age. 
This  terrace  was  laid  down  about  the  margin  of  the  Wicomico  forma- 
tion and  locally  is  believed  to  lap  up  on  the  thin  eroded  edges  of  the 
latter  which  are  supposed  to  run  out  a  short  distance  beneath  it.  It  is 
usually  separated  from  the  Wicomico  formation  by  a  well-defined  scarp, 


104 


THE   GEOLOGY   OP    CALVERT    COUNTY 


which  is  an  ancient  cliff  cut  by  the  waves  of  the  Talbot  sea  during  the 
post-Wicomico  subsidence,  but  this  relation  is  not  always  shown  (Plate 
IX,  Fig.  2). 

Local  Sections. 

The  materials  which  compose  the  Talbot  formation  vary  rapidly  from 
place  to  place.  The  following  sections,  however,  will  give  an  idea  of 
the  general  character  of  the  formation: 


Section  on  Patuxent  River  just  south  of  Hall  Creek. 

a   /•  Feet. 

o  5      Loam    2 

Pleistocene.     S  |  J  Yellowish  sandy  clay 4 

P  >-      Cross-bedded  sand  and  fine  gravel 10 

fe    I 

1 1 
Eocene.  ^  "5  J  Greensand  marl 

*  ^    -          Total 22 

Section  on  Patuxent  River  1.5  miles  south  of  Buena  Vista. 

Feet.   Inches. 

Yellowish  loam 2 

Reddish  yellow  clay 2 

Sandy  clay    2 

b      Gravel 1  6 

Pleistocene.     2  3  J  |an*     ', 2 

"3  g      Sandy   loam    1 

^  o      White  sand  6 

fe      Reddish  sand 1 

White  sand  1 

Greenish  sandy  clay  bearing  pebbles 2 

Total 15 

Section  on  Patuxent  River  .5  mile  south  of  Hellen  Gut. 

Feet.  Inches. 

r  Brownish  loam 3  6 

Gravel    2 

Coarse  sandy  clay  4 

Pleistocene.     ~  g  J  Very  coarse  sand 8 

EH  S      Fine  clay  sand 10 

£      Greenish  sandy  clay  bearing  vegetable  remains  which 

occur  at  tide  and  full  thickness  not  seen 1 

Total ,  .     28  6 


MARYLAND  GEOLOGICAL  SURVEY. 


CALVERT  COUNTY,   PLATE  VII. 


FlG.    I. — VIEW    SHOWING    SUNDERLAND    SURFACE    NEAR   HUNTINGTOWN. 


FlG.    2.— VIEW   SHOWING  SUNDERLAND-WICOMICO  SCARP,  WICOMICO  SURFACE  IN   FOREGROUND, 
HUNTING  CREEK  VALLEY. 


MARYLAND   GEOLOGICAL    SURVEY  105 

Section  on  Bay  Shore  .5  mile  south  of  Dares  Wharf. 

«![ 

Pleistocene.     5  |  -s  Variegated  cross-bedded  sand  and  gravel 33 

«if 

Miocene.  >  g  J  Greenish    sandy   clay    3 

3I1 

Total 36 

Section  on  Bay  Shore  one  mile  north  of  Drum  Point. 

Feet.  Inches. 

Yellowish  loam 2 

Cross-bedded  sand  and  gravel 24 

_      Coarse  gravel   6 

PipiQ  ,      11 J  Slate-colored  clay    5 

Peat  carrying  abundant  plant  remains 1  6 

Chocolate-colored  clay  carrying  gnarled  and  twisted 
plant  stems,  full  thickness  not  visible  as  it  passes 
below  beach  level  2 

Total ...  .35 


ORIGIN  OF  MATERIALS. 

The  sources  from  which  the  Sunderland,  Wicomico,  and  Talbot  seas 
derived  the  materials  for  their  respective  deposits  were  principally  con- 
fined to  the  Coastal  Plain.  The  waves  must  have  eroded  large  areas 
of  Cretaceous,  Eocene,  Miocene,  and  Lafayette  and  re-worked  the  ma- 
terials into  their  own  deposits.  In  addition  to  this,  the  Wicomico  sea 
had  the  Sunderland  deposits  on  which  to  erode  and  the  Talbot  sea  had 
both  the  Sunderland  and  Wicomico  land  surfaces  from  which  to  derive 
materials.  Wherever  the  Eocene  sands  and  marls  have  been  used  in  any 
considerable  quantity,  their  presence  is  indicated  by  a  peculiar  greenish 
color  imparted  to  the  deposit.  Miocene  materials  cannot  be  so  readily 
detected,  but  they  were  nevertheless  re-worked  in  large  quantities.  The 
rivers  also  brought  in  contributions  from  the  Piedmont  Plateau  and 
the  mountains  of  western  Maryland.  This  material  was  pushed  along 
the  bottom,  drifted  in  suspension,  and  floated  along  on  ice-blocks. 
8 


106  THE  GEOLOGY  OF  CALVERT  COUNTY 

INTERPRETATION  OP  THE  GEOLOGICAL  EECORD. 
SEDIMENTARY  RECORD  OF  THE  NANJEMOY  FORMATION. 
If  the  Nanjemoy  formation  in  Calvert  County  sustains  the  same  rela- 
tions to  the  rocks  which  lie  beneath  it  as  it  does  farther  to  the  north 
where  its  base  comes  to  the  surface,  it  must  rest  conformably  on  the  sur- 
face of  the  Aquia  formation,  and  the  Aquia  formation  is  believed  to 
rest  unconformably  on  the  eroded  edges  of  the  Upper  Cretaceous.  This 
would  indicate  that,  after  the  close  of  the  Upper  Cretaceous  cycle  of  sedi- 
mentation, Calvert  County  was  raised  above  the  ocean  and  extensively 
eroded;  it  was  then  depressed  and  submerged  beneath  the  Eocene  sea 
which  planed  down  the  somewhat  irregular  surface  of  Cretaceous  rocks 
and  deposited  on  them  the  materials  which  compose  the  two  Eocene 
formations.  The  depth  at  which  these  deposits  were  laid  down  cannot 
be  definitely  determined,  but  from  a  study  of  the  materials  which  com- 
pose them  and  the  fossils  which  they  contain,  it  is  believed  that  the  sea 
attained  a  depth  of  100  to  300  fathoms.  Deposits  v/ere  thus  made  at  a 
considerable  distance  from  the  shore  line  in  quiet  seas  and  probably 
accumulated  with  great  slowness. 

SEDIMENTARY   RECORD   OF    THE    CHESAPEAKE   GROUP. 

The  close  of  the  Nanjempy  epoch  was  marked  by  an  elevation  of  the 
region  which  brought  the  Eocene  deposits  above  the  ocean  and  exposed 
them  to  a  prolonged  attack  of  erosion.  After  the  region  had  suffered 
extensively  from  the  work  of  waves  and  rivers,  it  was  again  submerged 
beneath  the  ocean  and  the  materials  composing  the  Calvert  formation 
were  deposited.  As  the  Miocene  sea  advanced  little  by  little  on  the 
sinking  surface  of  the  mainland,  the  waves  caught  up  and  re-worked  the 
clays  and  greensands  of  the  various  Eocene  beds.  The  more  obdurate 
fossils  of  the  Eocene  survived  in  a  great  measure  the  erosive  work  along 
the  old  Miocene  shore  and  were  carried  out  and  deposited  in  deeper 
water.  They  may  now  be  seen  re-worked  in  the  basal  member  of  the 
Calvert  formation.  The  old  shore  line  of  the  Miocene  sea  which  was 
formed  during  the  Calvert  epoch  of  sedimentation  has  nowhere  been 


MARYLAND   GEOLOGICAL    SURVEY  107 

preserved  in  Maryland,  but  the  materials  which  composed  the  Calvert 
formation  in  this  county  were  deposited  in  seas  of  moderate  depth  in 
which  an  abundance  of  life  was  present,  as  is  shown  by  the  remains  of 
diatoms  and  the  extensive  beds  of  fossil  mollusks.  The  remains  of 
whales  and  other  cetaceans  show  that  these  vertebrates  abounded  in  the 
ocean,  and  the  discovery  of  a  bone  belonging  to  a  gannet  indicates  that 
birds  existed  along  the  nearby  shores.  This  particular  form  doubtless 
sought  its  food  in  the  sea  as  the  modern  fishing  gannets  do  at  the  present 
time. 

The  Calvert  epoch  was  brought  to  a  close  by  the  elevation  of  the  region 
once  more  above  the  level  of  the  ocean.  A  period  of  erosion  followed 
which  was  probably  of  short  duration  and  closed  with  the  depression  of 
the  region  again  beneath  the  sea.  Then  followed  the  deposition  of  the 
Choptank  and  St.  Mary's  formations,  in  which  conditions  similar  to 
those  just  described  for  the  Calvert  were  repeated. 

SEDIMENTARY    RECORD    OF    THE    COLUMBIA   GROUP. 

The  sedimentation  of  the  Chesapeake  Group  was  brought  to  a  close 
by  the  elevation  of  the  region  once  more  above  the  ocean.  After  an 
extensive  interval  of  erosion,  the  county  was  again  depressed  beneath 
the  waves.  This  was  the  period  in  which  the  Lafayette  deposits  were 
laid  down  and  subsequently  eroded  during  another  epoch  of  elevation, 
but  as  none  of  these  deposits  have  been  found  within  Calvert  County, 
this  particular  phase  of  the  history  will  not  be  discussed  in  this  place. 
The  deposits  which  lie  immediately  under  the  formations  of  the  Colum- 
bia Group  are  those  of  the  Chesapeake  Group. 

The  Sunderland,  Wicomico,  and  Talbot  formations  are  developed  in 
terraces  lying  one  above  the  other  in  vertical  range  from  tide  to  an  alti- 
tude of  about  180  feet.  Beneath  these  three  terraces,  there  is  forming 
to-day  a  fourth  which  extends  from  high-tide  downwards. 

The  key  to  their  interpretation  is  secured  by  studying  the  manner  in 
which  this  recent  terrace  is  forming.  At  the  present  time  the  waves  of 
the  Atlantic  Ocean  and  Chesapeake  Bay  are  engaged  in  tearing  away 
the  land  along  their  shores  and  in  depositing  the  detritus  on  a  submarine 


108  THE  GEOLOGY  OF  CALVEKT  COUNTY 

platform  or  terrace.  This  terrace  is  everywhere  present  and  may  be 
found  not  only  along  the  exposed  shores  but  also  passing  up  the  estuaries 
to  their  heads.  The  materials  are  extremely  variable.  Along  the  un- 
broken coast  the  detritus  has  a  local  character,  while  near  river  mouths, 
the  terrace  is  composed  of  the  debris  contributed  from  the  river  basin. 

In  addition  to  building  a  terrace,  the  waves  of  the  Atlantic  and  the 
Chesapeake  are  cutting  a  sea-cliff  along  their  coast  line.  The  height  of 
this  cliff  depends  not  only  on  the  force  of  the  breakers  but  also  on  the 
relief  of  the  land  against  which  the  waves  beat.  A  low  coast  line  yields 
a  low  sea-cliff,  and  a  bold  coast  line,  a  high  one,  and  each  passes  into 
the  other  as  often  and  as  rapidly  as  the  topography  changes,  so  that  as 
one  travels  along  the  shore  of  Chesapeake  Bay  high  cliffs  and  low  de- 
pressions are  passed  successively.  The  wave-built  terraces  and  the  wave- 
cut  cliffs  are  important  features  along  the  entire  extent  of  the  Bay 
shore,  and  should  be  sought  for  wherever  other  terrace  surfaces  are 
studied.  It  must,  however,  be  borne  in  mind  that  there  are  places 
along  the  Bay  shore  where  the  sea-cliff  is  absent,  or  so  low  that  it  does 
not  form  a  conspicuous  feature  in  the  topography.  In  addition  to  these 
features,  bars,  spits,  and  other  wave  and  current-built  formations  of  a 
similar  character  are  frequently  met  with. 

If  the  present  coast  line  should  be  elevated,  the  submerged  platform 
which  is  now  forming  would  appear  as  a  well-defined  terrace  of  variable 
width  with  a  surface  sloping  gently  toward  the  water.  This  surface 
would  fringe  the  entire  Atlantic  and  Bay  shores  as  well  as  those  of  all 
the  estuaries.  The  sea-cliff  would  at  first  be  sharp  and  easily  distin- 
guished, but  as  time  passed,  the  least  conspicuous  portions  would  gradu- 
ally yield  to  the  levelling  influences  of  erosion,  and  might  gradually  dis- 
appear altogether.  Erosion  would  also  destroy  in  large  measure  the 
original  continuity  of  the  formation,  but  as  long  as  portions  of  it  re- 
mained, the  old  surface  could  be  reconstructed  and  the  history  of  its  origin 
determined. 

If  the  topographic  and  geologic  features  which  are  associated  with  the 
terrace  now  forming  are  compared  with  those  which  accompany  the 
various  terraces  of  the  Columbia  group,  the  analogy  is  found  to  be  so 


MARYLAND   GEOLOGICAL   SURVEY  109 

striking  that  the  conclusion  regarding  a  common  origin  of  both  is  irre- 
sistible, and  there  can  be  no  reasonable  doubt  that  the  mode  of  formation 
of  the  modern  terrace  furnishes  the  key  to  the  interpretation  of  the 
ancient. 

The  subsidence  of  the  Atlantic  Coastal  Plain,  which  carried  down  be- 
neath the  ocean  level  the  entire  surface  of  Calvert  County,  gave  oppor- 
tunity to  the  waves  to  finish  the  destruction  of  such  portions  of  the 
Lafayette  formation  as  chanced  to  survive  the  erosive  work  of  the  streams. 
As  Calvert  County  sank  slowly  beneath  the  water,  the  shore  of  the  ad- 
vancing Atlantic  gradually  worked  farther  and  farther  landward  until 
it  had  passed  beyond  the  bounds  of  Calvert  County  and  finally  came  to 
rest  near  the  borders  of  the  Piedmont  far  to  the  westward.  Calvert 
County  at  that  time  was  being  rapidly  covered  by  an  off-shore  deposit  of 
mud,  sand,  gravel,  and  ice-borne  boulders  which  were  floated  down  the 
rivers  on  huge  ice-blocks.  How  long  the  sea  remained  in  this  posi- 
tion is  not  definitely  known,  but  it  is  certain  that  it  remained 
long  enough  for  the  waves  of  the  Sunderland  sea  to  cut  a  well-pronounced 
scarp  against  the  Lafayette  and  older  formations  north  and  west  in 
regions  beyond  the  bounds  of  Calvert  County.  These  ancient  sea-cliffs 
are  to-day  prominent  features  of  the  topography  of  southern  Maryland 
and  may  be  mapped  as  easily  as  the  sea-cliff  which  is  now  being  cut  by 
the  waves  of  Chesapeake  Bay  and  its  estuaries. 

While  the  Sunderland  off-shore  deposits  were  still  in  progress  of  for- 
mation over  the  surface  of  Calvert  County,  the  region  rose  again  above 
the  surface  of  the  water  and  erosion  began  vigorously  to  cut  away  the 
loose  sands  and  gravels  which  had  been  previously  deposited.  How 
extensive  this  uplift  was,  it  is  now  quite  impossible  to  say.  It  is  equally 
difficult  to  determine  its  duration,  but  it  was  of  sufficient  length  to  per- 
mit the  destruction  of  a  large  portion  of  this  Sunderland  formation,  for 
many  of  the  larger  streams  within  Calvert  County  opened  up  deep  val- 
leys within  it.  As  has  been  pointed  out  before,  the  streams  which  were 
chiefly  instrumental  in  this  destructive  work  were  Lyons,  Hall,  Hunting, 
Fishing,  Parker,  Battle,  Island,  and  St.  Leonard  creeks.  The  question 
as  to  whether  the  Patuxent  Eiver  first  came  into  existence  at  this  time  or 


no 


THE   GEOLOGY   OF    CALVERT    COUNTY 


previously  in  the  erosive  interval  which  followed  the  uplift  of  the  La- 
fayette formation  has  been  discussed  elsewhere. 

After  Calvert  County  had  been  subjected  to  erosion  for  a  certain 
period,  it  was  again  submerged,  but  not  to  the  same  extent  as  in  the 


FIG.  2. — Diagram  showing  approximate  position  of  shore  line  of  Wicomico 

sea. 

previous  cycle,  during  the  deposition  of  the  Sunderland  formation. 
The  subsidence,  however,  was  sufficient  to  drown  the  rivers  which 
had  opened  up  their  valleys  across  the  county  and  to  transform  these 
into  estuaries,  so  that  a  waterway  extended  across  Calvert  County 


MARYLAND   GEOLOGICAL    SURVEY 


111 


from  what  is  now  the  mouth  of  Pishing  Creek  to  the  mouth  of  Hunting 
Creek.  Another  waterway  from  the  south  ran  from  Drum  Point  south- 
westward  to  what  is  now  the  head  of  the  Hunting  Creek  estuary,  and  a 
third  extended  from  what  is  now  the  mouth  of  Parker  Creek  across  the 


FIG.  3. — Diagram  showing  approximate  position  of  shore  line  of  Talbot  sea. 

divide  to  Battle  Creek.  Other  streams  of  less  importance  were  also  trans- 
formed into  estuaries,  so  that  the  county  presented  a  most  irregular 
shore  line  and  the  lower  half  of  the  region  was  transformed  into  a  group 
of  small  irregular  islands.  The  subsidence  at  this  time  amounted  to 
about  90  feet.  As  the  county  remained  at  this  level  for  some  little 


112  THE   GEOLOGY   OF    CALVERT    COUNTY 

time,  the  waves  along  the  shore  had  an  opportunity  to  do  considerable 
erosive  work  and  forced  the  shore  lines  back  toward  the  rivers,  widening 
the  valleys  which  had  been  previously  opened  during  the  erosive  interval 
which  followed  the  uplift  of  the  Sunderland  formation.  The  material 
which  was  derived  from  the  wave  erosion  was  deposited  along  the  floor 
of  these  estuaries,  filling  them  in  to  a  considerable  extent  and  raising 
them  up  to  a  higher  level  than  that  which  they  possessed  when  the 
country  was  submerged  at  the  beginning  of  the  epoch.  While  this  pro- 
cess of  sedimentation  was  still  in  progress,  the  country  once  more  rose 
above  the  level  of  the  waves  and  permitted  the  streams  to  cut  again  in 
their  old  valleys.  This  epoch  of  elevation  was  apparently  a  short  one 
for  there  was  not  enough  time  to  enable  the  streams  to  completely  re- 
establish themselves  throughout  the  entire  length  of  their  former  valleys. 
They  had  only  partially  begun  the  erosive  work  when  the  country  was 
once  more  submerged  beneath  the  waves  and  the  deposition  of  the  Talbot 
terrace  was  begun.  At  this  time,  the  streams  were  once  more  transformed 
into  estuaries,  but  not  to  the  extent  which  they  were  in  the  previous 
Wicomico  cycle  of  deposition.  The  land  did  not  sink  more  than  45  feet 
below  its  present  altitude  and  remained  there  for  only  a  short  time  when  it 
was  once  more  raised  and  eroded.  This  epoch  of  elevation  was  the  one 
which  ushered  in  the  present  cycle  of  events  and  permitted  the  cutting 
of  the  Eecent  sea-cliff.  Since  its  initiation,  the  land  has  once  more  as- 
sumed a  downward  motion,  and  the  entire  coast  line  in  this  region  seems 
to  be  sinking  once  more  beneath  the  level  of  the  waves. 

Along  the  shore  of  Chesapeake  Bay  and  the  lower  courses  of  many 
of  its  estuaries  there  occur  at  intervals  deposits  of  greenish-blue  clay 
developed  as  lenses  in  the  body  of  the  Talbot  formation.  Usually  the 
base  of  the  clay  is  not  visible  but  its  stratigraphic  relations  are  such  as 
to  leave  no  doubt  that  it,  or  a  thin  gravel  bed  on  which  it  occasionally 
rests,  is  uncomformable  on  whatever  lies  beneath.  The  upper  surface 
of  these  clay  lenses  is  everywhere  abruptly  terminated  by  a  bed  of  coarse 
sand  or  gravel  which  grades  upwards  into  loam  and  at  its  contact  with 
the  clay  strongly  suggests  an  unconformity.  These  clay  lenses  are  in 
some  localities  devoid  of  fossils  but  in  others  they  contain  remains  of 


MARYLAND  GEOLOGICAL  SURVEY. 


CALVERT  COUNTY,  PLATE  VIII. 


MARYLAND   GEOLOGICAL   SURVEY  113 

marine  and  estuarine  animals  and  land  plants.  Many  localities  for  these 
clays  are  already  known  and  as  exploration  advances  new  ones  are  fre- 
quently discovered.  Some  of  the  more  typical  exposures  will  now  be 
described. 

Along  the  shore,  about  a  mile  below  Bodkin  Point,  Anne  Arundel 
County,  the  variegated  clays  of  the  Earitan  formation  are  finely  exposed 
in  a  cliff  some  30  feet  in  height.  These  clays  occupy  the  greater  portion 
of  the  section  and  carry  an  abundance  of  lignite  more  or  less  incrusted 
with  crystals  of  pyrite.  Sands  and  gravels  of  the  Talbot  formation  un- 
conf ormably  overlie  the  clays  and  constitute  the  upper  portion  of  the  cliff. 
Half  a  mile  farther  south  the  cliff  still  maintains  its  former  height,  but 
the  section  has  changed.  Some  ancient  stream  must  have  established  its 
valley  on  the  Raritan,  for  here  the  surface  of  that  formation,  like  a  great 
concave  depression,  passes  gradually  beneath  the  beach  to  appear  again 
in  the  cliff  150  yards  to  the  south.  In  this  hollow,  lying  unconf ormably 
on  the  Raritan  formation,  is  a  bed  of  dark-colored  clay  about  15  feet 
thick.  Bluish  and  greenish  tinted  bands  of  clay  relieve  somewhat  its 
somber  aspect,  and  at  about  its  middle  portion  it  carries  a  bed  of  peat. 
But  its  most  striking  feature  is  the  presence  of  huge  fossil  cypress  knees 
and  stumps  which  are  imbedded  in  its  lower  portion.  These  stumps 
vary  in  diameter  from  2  to  over  10  feet,  and  after  the  removal  of  the 
surrounding  clay,  stand  out  prominently  in  the  position  in  which  they 
must  have  grown.  Mr.  A.  Bibbins,  to  whom  the  author  is  indebted  for 
notes  on  these  deposits,  has  counted  32  of  these  stumps  which  were 
visible  at  one  time,  and  also  reports  finding  worm-eaten  beechnuts  inti- 
mately associated  with  cypress  cones  near  the  base  of  the  formation. 
Sands  and  gravels  of  the  Talbot  formation  overlie  the  whole.  Imme- 
diately south  of  this  outcrop  the  dark-colored  clays  are  temporarily  re- 
placed by  the  Earitan  formation,  but  they  appear  again  a  little  farther 
down  the  shore,  and  afford  an  almost  unbroken  exposure  for  about  a  mile. 
The  thickness  of  the  clay  in  this  locality  is  at  first  about  10  or  12  feet, 
but  it  gradually  becomes  thinner  southward  and  finally  disappears  alto- 
gether. Casts  of  Unio  shells  and  not  vegetable  remains,  are  its  pre- 
dominant fossils,  while,  like  the  beds  containing  the  cypress  swamp,  it 


114  THE    GEOLOGY    OF    CALVEET    COUNTY 

overlies  the  Raritan  formation  unconformably,  and  is  itself  abruptly 
buried  beneath  Talbot  sands  and  gravel. 

Another  locality  is  on  the  Bay  shore,  about  a  mile  northeast  of  Drum 
Point.  Here,  at  the  base  of  a  cliff  about  30  feet  high,  is  a  2-foot  bed 
of  dark,  chocolate-colored  clay  carrying  gnarled  and  twisted  sticks  pro- 
truding in  every  direction  from  the  material  in  which  they  are  imbedded. 
Above  this  occurs  a  thin  seam  of  lignite  1£  feet  thick,  which  in  turn  is 
overlain  with  about  5  feet  of  slate-colored  clay.  At  this  point  the  con- 
tinuity of  the  deposit  is  interrupted  by  a  series  of  sands,  clays,  and 
gravels  belonging  to  the  Talbot  formation,  which  extend  upward  to  the 
top  of  the  cliff.  Although  the  base  of  this  lignitic  clay  series  is  buried 
beneath  beach  sands,  field  relations  lead  to  the  conclusion  that  the  de- 
posit is  very  much  younger  than  the  Miocene  clays  on  which  it  rests  un- 
conformably.  A  similar  section  is  to  be  seen  on  the  Patuxent  River, 
about  a  mile  below  Sollers  Landing.  Large  stumps  here  protrude  from 
a  dark,  basal  clay  bed,  some  5  feet  in  thickness,  which  is  covered  by  3 
feet  of  sand,  and  this  again  is  buried  beneath  10  feet  of  Talbot  sand 
and  gravel.  The  relations  of  the  basal  clay  to  the  underlying  Miocene 
is  again  obscure,  but  indications  point  to  an  unconformity.  Another 
section  is  exposed  along  the  shore  1£  miles  northwest  of  Cedar  Point, 
where  a  thin  bed  of  drab  clay  carrying  vegetable  remains  is  overlain 
abruptly  with  sands  and  gravels.  Its  contact  with  the  Miocene  is  again 
unfortunately  obscure.  At  the  localities  just  described  no  animal  re- 
mains have  been  discovered,  but  on  the  north  bank  of  the  Potomac,  about 
half  way  between  St.  Mary's  River  and  Breton  Bay,  there  is  a  deposit  of 
lead-colored  clay,  exposed  for  a  quarter  of  a  mile  along  the  shore.  It  is 
buried  at  each  end  as  well  as  above  by  sands  and  gravels  and  carries  both 
lignite  and  Rangia  cuneata  (Conrad).  Although  the  description  given 
by  Conrad  is  somewhat  vague,  it  is  highly  probable  that  he  visited  this 
locality  and  collected  specimens  of  the  fossils.  Two  more  localities 
still  remain  to  be  mentioned,  Cornfield  Harbor,  and  its  companion  de- 
posit exposed  5|  miles  south  of  Cedar  Point  on  the  Bay  shore.  Conrad 
was  well  acquainted  with  these  deposits  and  to  the  former  he  devoted 
special  attention.  Each  is  about  10  feet  thick,  occurs  at  the  base  of  a 


MARYLAND    GEOLOGICAL    SURVEY  115 

low  cliff,  is  composed  mostly  of  a  dark,  lead-colored  clay,  and  is  overlain 
abruptly  with  Talbot  sand  and  gravel,  while  unconformity  on  the  Miocene 
is  beautifully  shown  at  the  base  of  the  Bay  shore  section.  A  number  of 
fossils  have  been  described  from  the  Cornfield  Harbor  locality,  among 
which  are  Ostrea  virginica  Gmelin,  Area  ponderosa  Say,  Area  transversa 
Say,  Venus  mercenaria  Linne,  Mya  arenaria  Linne,  Barnea  costata 
(Linne),  Crepidula  plana  Say,  Polynices  duplicatus  (Say),  and  Fulgur 


FIG.  4. — Diagram  showing  pre-Talbot  valley. 

carica  (Gmelin).  In  this  exposure  the  lower  4  feet  of  clay  carries  the 
marine  forms  and  above  this  there  are  2  feet  of  sandy  clay  literally  packed 
with  Ostrea  virginica.  These  same  general  relations  hold  for  the  similar 
deposits  south  of  Cedar  Point. 

The  stratigraphic  relation  of  these  lenses  of  clay  which  are  surely 
unconformable  on  the  underlying  formation  and  apparently  so  with  the 
overlying  sand  and  loams  of  the  Talbot  formation  is  a  problem  which 
engaged  the  attention  of  the  author  until  it  appeared  that  the  apparent 
unconformity  with  the  Talbot,  although  in  a  sense  real,  does  not,  how- 


116 


THE   GEOLOGY   OF    CALVERT    COUNTY 


ever,  represent  an  appreciable  lapse  of  time  and  that  therefore  the  clay 
lenses  are  actually  a  part  of  that  formation.  In  order  to  understand 
more  clearly  what  is  believed  to  have  taken  place,  these  clay  deposits 
should  be  divided  into  two  groups,  those  which  carry  plant  remains  con- 
stituting one,  and  those  containing  marine  and  brackish-water  fossils 
the  other.  Such  as  are  devoid  of  fossils  may  belong  to  either  one  of  the 
groups  according  to  their  situation  but  probably  more  frequently  belong 
to  the  latter. 


FIG.  5. — Diagram  showing  advancing  Talbot  shore-line  and  ponded  stream. 

In  a  word,  the  clays  carrying  plant  remains  are  regarded  as  lagoon 
deposits  made  in  ponded  stream-channels  and  gradually  buried  beneath 
the  advancing  beach  of  the  Talbot  sea.  The  clays  carrying  marine  and 
brackish-water  organisms  are  believed  to  have  been  at  first  off-shore 
deposits  made  in  moderately  deep  water  and  later  brackish-water  de- 
posits made  behind  a  barrier-beach  and  gradually  buried  by  the  advance 
of  that  beach  toward  the  land.  Taking  up  the  first  class  of  deposits  in 
more  detail  -they  are  believed  to  have  been  formed  in  the  following 
manner : 


MARYLAND   GEOLOGICAL    SURVEY 


117 


During  the  erosion  interval  which  immediately  preceded  the  deposition 
of  the  Talbot  formation  many  streams  cut  moderately  deep  channels  in 
the  land  surface,  which  on  the  sinking  of  the  region  again  were  trans- 
formed into  estuaries  (Fig.  4).  Across  the  mouths  of  the  smaller  of 
these  drowned  valleys  the  shore  currents  of  the  Talbot  sea  rapidly  built 
bars  and  beaches  which  ponded  the  waters  behind  them  and  transformed 
them  from  brackish-water  estuaries  to  fresh-water  lagoons.  These  la- 


FIG.  6. — Diagram  showing  later  stage  in  advance  of  Talbot  shore-line. 

goons,  however,  were  gradually  changed  into  marshes  and  possibly  to 
meadows  by  the  inflow  of  detritus  from  the  surrounding  region  and  on 
the  new  land  surface  thus  formed  various  kinds  of  vegetation  took  up 
their  abode  (Pig.  5).  At  first  the  beach-sands  advanced  in  the  lagoon 
and  filled  up  completely  that  portion  of  the  submerged  trough  which 
lay  immediately  beneath  them,  but  later,  as  the  lagoon  was  silted  up 
more  and  more  with  mud  derived  from  the  surrounding  basin,  the  ad- 
vancing beach  came  to  rest  on  this  lagoon  deposit  as  a  foundation  and 
arrived  at  length  at  the  point  where  the  lagoon  had  been  filled  up  to 


118  THE   GEOLOGY   OF   CALVEKT   COUNTY 

the  level  of  wave-base  or  higher.  When  this  place  was  reached  another 
process  was  added  to  that  of  beach  andvance.  Heretofore  the  waves  and 
wind  had  been  simply  pushing  forward  material  over  the  advancing  front 
but  now  the  mud  deposit  in  the  lagoon  had  actually  reached  the  level  of 
wave-work  and  had  transformed  the  lagoon  from  a  pond  to  a  marsh  or  to 
a  meadow,  the  breakers  attacked  the  upper  portion  of  the  lagoon  deposit 
and  eroded  it  down  to  the  level  of  wave-base  as  rapidly  as  they  could 
reach  it  from  under  the  superficial  veneer  of  the  beach-sands.  Cypress, 
cat-tails,  sedges,  and  other  vegetation  which  had  taken  up  their  abode 
in  the  marsh  would  be  overwhelmed  with  detritus  by  the  advancing  beach 
and  a  little  later  be  destroyed  by  the  breakers.  In  this  way  all  traces 
of  life  must  be  removed  from  the  deposit  except  such  as  happened  to 


FIG.  7.— Ideal  section  showing  advance  of  Talbot  shore-line. 

occupy  a  position  lower  than  wave-base.  One,  therefore,  finds  preserved 
in  the  clay  water-logged  trunks  and  leaves,  nuts,  etc.,  and  roots  of  huge 
trees  like  the  cypress.  The  area  over  which  the  waves  had  removed  the 
upper  portions  of  the  lagoon  deposit  can  be  determined  not  only  by  the 
presence  of  truncated  stumps  but  also  by  the  character  of  the  contact. 
Here  there  is  a  sharp  division  between  the  clay  and  the  overlying  sand 
and  gravel  while  the  area  over  which  the  beach  advanced  without  cutting 
would  be  indicated  by  a  partial  mingling  of  the  beach  material  with 
lagoon  mud. 

A  still  later  stage  in  the  process  is  illustrated  in  the  accompanying 
diagram  (Fig.  6)  which  represents  a  stage  where  the  waves  have  so  far 
advanced  as  to  largely  destroy  the  original  stream  channel.  A  small 
portion  of  the  old  lagoon  still  exists  at  the  head  of  the  swamp  but  its 
lower  portions  have  long  since  been  submerged  and  covered  over  by  the 


MARYLAND   GEOLOGICAL   SURVEY  119 

advancing  beach.  The  transverse  section  shows  what  is  left  of  the 
lagoon  deposits  of  mud  carrying  truncated  stumps  of  cypress  and  other 
trees  which  happened  to  be  buried  deep  enough  to  escape  the  destructive 
powers  of  the  breakers.  The  broken  line  indicates  the  outline  of  the  clay 
lens.  Fig.  7  is  a  section  through  the  same  region  made  at  right  angles 
to  the  one  just  described.  At  D  the  breakers  are  forcing  forward  the 
beach  upon  the  meadow.  Just  off  from  the  beach  the  waves  have  swept 
away  the  sand  and  are  eroding  on  the  lagoon  mud  which  reached  out  to 
them  under  the  beach  veneer.  At  C  the  waves  have  succeeded  in  cutting 
down  the  lagoon  deposit  to  wave-base  and  have  left  behind  a  thin  veneer 
of  sand  and  gravel  as  the  sinking  land  carries  it  below  the  reach  of  the 
waves.  At  B  the  lagoon  deposit  was  not  thick  enough  to  reach  the  zone 
of  wave-erosion  and  simply  grades  up  into  a  thick  deposit  of  sand  and 
loam  which  passes  out  toward  A. 

The  second  category  of  clay  lenses,  namely  those  carrying  marine  and 
brackish-water  organisms  are  understood  to  have  been  formed  in  a 
somewhat  different  manner.  The  lower  portion  carrying  the  marine 
organisms  points  to  salt-water  conditions  and  contains  remains  of  sea 
animals  which  live  to-day  along  the  Atlantic  coast.  At  the  time  when 
this  deposit  was  formed,  the  ocean  waters  had  free  access  to  the  region 
and  the  blue  mud  in  which  they  are  now  imbedded  and  in  which  they 
lived  was  a  quiet-water  deposit  laid  down  some  distance  from  the  land. 
Later,  however,  it  would  appear  that  a  barrier  beach  was  constructed 
shutting  off  a  portion  of  the  sea-bed  which  had  formerly  been  occupied 
by  marine  animals  and  gradually  allowing  it  to  be  transformed  from 
salt-water  conditions  to  those  of  brackish  water.  In  this  brackish-water 
lagoon  the  fauna  changed  to  that  found  along  our  estuaries  to-day  and 
huge  oysters  nourished  and  left  behind  them  a  deposit  of  shell-rock. 
With  the  bar  advancing  landward  this  lagoon  was  gradually  filled  up 
with  sand  and  gravel  and  finally  obliterated. 

The  upper  unconformity,  then,  in  the  case  of  the  fresh-water  and  the 
brackish-water  lagoons  is  real  only  in  the  sense  that  an  unconformity  in 
a  cross-bedded  wave-  and  delta-deposit  is  real.  There  is,  it  is  true,  a  lack 
of  harmony  in  the  position  of  the  beds  and  a  sharp  break  is  indicated 


120  THE  GEOLOGY  OF  CALVEET  COUNTY 

but  there  is  no  indication  of  an  appreciable  time-lapse  between  the 
clay  and  the  oyster-bed  on  the  one  hand  and  the  overlying  sands  and 
gravel  on  the  other,  and  the  sea  which  eroded  the  clay  to  a  fixed  level 
immediately  afterwards  overspread  the  surface  of  the  same  with  a  veneer 
of  beach  sand.  There  is,  therefore,  no  time  break  indicated  by  this 
unconformity  and  the  lenses  of  swamp-clay  as  well  as  those  carrying 
marine  and  brackish-water  organisms  are  to  be  looked  upon  not  as 
records  of  elevation  and  subaerial  erosion  but  as  entombed  lagoon- 
deposits  made  in  an  advancing  sea  and  contemporaneous  with  the  other 
portions  of  the  formation  in  whose  body  they  are  found. 

The  hypothesis  here  advanced  is  based  on  and  reinforced  by  many 
observations  along  the  present  shores  of  the  Atlantic  Ocean,  Chesapeake 
Bay,  and  its  estuaries.  Each  step  in  the  process  described  above  is  there 
illustrated  and  some  of  them  are  met  with  again  and  again. 

As  one  passes  along  the  shores  of  Chesapeake  Bay  and  of  the  rivers  which 
flow  into  it,  stream  channels  are  continually  met  which  have  arrived  at 
more  or  less  advanced  stages  in  the  above-mentioned  process.  Some  are 
in  part  converted  into  lagoons,  by  bars  built  across  their  mouths,  others 
show  partial  filling  by  mud  washed  in  from  the  surrounding  country, 
and  still  others  have  reached  the  advanced  stage  of  swamps  or  meadows 
in  which  various  types  of  vegetation  are  flourishing.  In  addition  to  the 
usual  undergrowth  which  is  found  in  wet  places,  the  cypress  has  taken 
up  its  abode  in  these  bogs  and  has  converted  some  of  them  into  cypress 
swamps.  For  great  stretches  along  the  shore  the  advance  of  the  sea  is 
indicated  by  well-washed  cliffs  while  in  other  places  the  waves  are  found 
devouring  beds  of  clay  which  are  situated  immediately  in  front  of  lagoon 
swamps  and  separated  therefrom  by  nothing  but  a  low  superficial  beach. 
These  clay  beds  invariably  lie  at  and  below  water-level,  are  very  young 
in  age,  and  evidently  pass  directly  under  the  beach  to  connect  with  the 
lagoon-clay  beyond.  This  interpretation  is  made  the  more  certain  by 
the  presence  of  roots  in  the  wave-swept  clays  which  but  a  short  time 
before  belonged  to  living  plants  identical  with  those  now  flourishing 
behind  the  beach,  and  point  to  a  time  not  far  distant  when  they  also 
were  a  part  of  the  lagoon  swamp  behind  a  beach  situated  a  little  farther 


MARYLAND  GEOLOGICAL  SURVEY. 


FlG.    I. — VIEW   SHOWING   TALBOT  FORMATION    NEAR  DARES   WHARF. 


FlG.    2. — VIEW    SHOWING    WICOMICO-TALBOT    SCARP    ALONG    PATUXENT    RIVER    SOUTH    OF 
COCKTOWN   CREEK. 


MARYLAND   GEOLOGICAL    SURVEY  121 

seaward.  At  Chesapeake  Beach  a  ditch  has  been  cut  through  one  of 
these  beaches  which  shows  a  continuous  deposit  of  clay  from  a  lagoon 
swamp  passing  out  under  the  beach  to  the  Bay  beyond.  The  waves  are 
thus  caught,  as  it  were,  in  the  act  of  eroding  the  upper  portion  of  the 
lagoon  deposit. 

From  a  large  body  of  data  gained  from  over  a  wide  area,  it  is  evident 
that  the  erosion  which  occurred  during  the  interval  between  the  eleva- 
tion of  the  Talbot  terrace  and  the  present  subsidence  of  the  coast  was 
sufficient  to  permit  streams  to  cut  moderately  deep  valleys  in  the  former. 
It  would  then  appear  that  as  the  region  was  gradually  lowered  again 
beneath  the  present  ocean  the  upper  portions  of  the  stream-channel  in 
time  passed  below  wave-base  and  whatever  has  collected  in  them  since 
that  period  will  be  preserved  beneath  the  advancing  sea  as  a  more  or 
less  fossiliferous  clay  lens  apparently  unconformable  beneath  beach 
debris. 

The  barrier  beaches  which  exist  at  intervals  along  the  Atlantic  coast 
of  New  Jersey,  Delaware,  Maryland,  Virginia,  and  southward  show  us 
how  portions  of  the  ocean-bed,  which  were  formerly  bathed  by  salt  water 
and  sustained  a  marine  fauna,  are  now  converted  to  lagoons  behind 
barrier  beaches,  and  have  passed  over  in  varying  degrees  to  brackish- 
water  conditions  bearing  estuarine  faunas. 

Similar  deposits  to  those  just  described  have  been  seen  by  the  author 
along  the  Rappahannock  River,  especially  at  Mosquito  Point,  and  there 
is  no  reason  to  doubt  that  they  occur  in  many  other  places  along  Chesa- 
peake Bay  and  its  estuaries,  within  the  State  of  Virginia.  From  analogy, 
it  would  be  expected  that  similar  deposits  would  be  discovered  along 
Delaware  Bay  where  conditions  must  have  been  identical  with  those  which 
prevailed  in  Chesapeake  Bay.  That  such  deposits  do  occur  along  the 
shores  of  the  Delaware  there  can  be  no  doubt.  The  most  noted  of  these 
is  at  Fish  House  on  the  New  Jersey  side  of  the  Delaware  River  a  few 
miles  above  Philadelphia. 


THE  ECONOMIC  RESOURCES  OF  CALVERT 
COUNTY 


BY 

BENJAMIN    L.    MILLER 


INTRODUCTORY. 

The  economic  resources  of  Calvert  County  are  neither  varied  nor 
especially  valuable  yet  several  of  them  are  worthy  of  more  attention  than 
they  have  thus  far  received.  Aside  from  the  soils,  which  are  foremost 
in  importance  and  value  and  which  are  discussed  in  a  subsequent  chapter, 
the  county  contains  several  deposits  of  considerable  economic  value,  none 
of  which  are,  at  present,  utilized  to  their  fullest  extent.  These  are 
the  clays,  sands,  gravels,  glauconitic  and  shell  marls,  and  diatomaceous 
earth.  In  addition,  valuable  water  resources  contribute  much  to  the 
mineral  wealth  of  the  region. 

Almost  all  of  these  products  have  an  especial  value  to  the  residents 
of  the  county  in  that  they  either  contain  ingredients  for  soil  enrichment 
or  materials  for  the  construction  of  good  roads.  Since  agriculture  is 
the  chief  occupation  it  is  believed  that  the  general  recognition  of  the 
value  of  the  natural  products  of  the  region  will  lead  to  their  greater 
use.  This  would  eventually  enhance  farm  lands  through  increased  soil 
fertility  and  easier  land  transportation. 

THE  NATURAL  DEPOSITS. 

THE  CLAYS. 

The  clays  constitute  the  most  valuable  economic  deposits  of  the  region. 
As  already  stated  in  a  preceding  chapter  on  the  stratigraphy,  several 
formations  represented  in  the  county  contain  considerable  quantities  of 
clay.  These  argillaceous  beds  are  quite  generally  distributed  although, 


124  THE   ECONOMIC    RESOURCES   OF    CALVERT    COUNTY 

so  far  as  known  the  clay  has  been  used  for  the  manufacture  of  brick  in 
only  one  locality.  It  is  not  suitable  for  pottery  or  the  finer  grades 
of  brick  but  makes  a  fairly  good  variety  of  common  red  brick.  Since 
the  clay  supplies  are  ample  there  seems  to  be  no  good  reason  why  the 
county  should  not  produce  all  the  brick  and  tile  of  this  character  required 
for  local  uses.  Should  a  ready  market  be  found  and  better  means  of 
transportation  obtained,  brick  for  shipment  might  perhaps  be  produced 
at  a  profit:  However,  since  other  counties  in  the  State  more  favorably 
situated  with  respect  to  markets  and  the  main  lines  of  railroads  contain 
equally  extensive  clay  deposits,  sometimes  of  a  better  quality,  it  is  not 
probable  that  Calvert  County  will  ever  become  an  important  clay  center. 
It  should,  however,  produce  enough  brick  to  supply  the  local  demand. 

Should  the  experiments  that  are  being  tried  elsewhere  of  using  burned 
clay  for  road  metal  prove  to  be  successful  some  of  the  clay  of  the  county 
may  be  profitably  used  in  this  way.  Since  the  sandy  roads  seriously 
interfere  with  the  development  of  the  region  there  will  undoubtedly  be 
an  increased  demand,  sooner  or  later,  for  cheap  road  metal,  and  it  is 
possible  that  the  clay  of  this  region  may  partially  meet  this  demand. 
The  clays  occur  in  deposits  of  both  Tertiary  and  Quaternary  age. 

TERTIARY  CLAYS. — Although  argillaceous  beds  occur  very  frequently 
in  the  Eocene  and  Miocene  strata  of  the  State,  in  general  they  are  too 
sandy  to  be  of  much  economic  importance.  This  is  especially  true  of  the 
Eocene  in  Calvert  County.  The  only  important  clay  member  in  the 
Eocene  of  the  State,  the  pink  Marlboro  clay,  although  well  exposed  along 
the  Patuxent  Eiver  about  four  miles  north  of  the  county  line,  here  lies 
beneath  tide.  It  is  covered  by  the  arenaceous  glauconitic  beds  exposed 
in  the  vicinity  of  Lyons  Creek. 

The  Calvert,  Choptank,  and  St.  Mary's  formations  of  the  Miocene  all 
contain  beds  of  sandy  clay  which  are  well  exposed  in  many  places  along 
the  Calvert  Cliffs  and  in  the  stream  valleys.  The  Calvert,  which  out- 
crops in  the  northern  half  of  the  county,  contains  more  of  this  clay  than 
do  the  other  Miocene  formations,  and  the  clay  is  less  sandy.  It  is 
bluish-green  to  black  when  fresh,  but  becomes  lighter  in  color  on  exposure. 
It  has  never  been  worked  and  is  probably  of  little  economic  value  because 


MARYLAND    GEOLOGICAL    SURVEY  125 

of  its  large  percentage  of  sand,  iron,  and  lime.  The  lime  is  derived  from 
the  numerous  fossil  shells  which  are  either  generally  distributed  through- 
out the  sandy  clay  or  massed  in  definite  shell  beds  within  it. 

QUATERNARY  CLAYS. — The  clays  of  the  surficial  formations  of  the 
county  greatly  exceed  in  value  those  of  the  underlying  deposits  and  are 
found  in  each  of  the  three  Pleistocene  members.  Their  mode  of  occur- 
rence is  very  similar  in  the  different  formations  as  is  also  their  general 
character.  The  clays  occur  in  the  form  of  a  surface  capping  of  clay 
loam  representing  the  last  stage  of  deposition  in  each  epoch,  and  as  lenses 
of  light  drab  to  dark  brown  clay  contained  in  the  body  of  the  deposits. 
In  all  probability  the  surface  loam  was  not  everywhere  developed  and 
often  where  it  was  once  present  it  has  since  been  removed  by  erosion,  so 
that  it  is  by  no  means  co-extensive  with  the  various  Pleistocene  forma- 
tions of  which  it  forms  a  part.  It  is  extremely  variable  in  thickness, 
ranging  from  a  few  inches  to  6  or  8  feet  in  Calvert  County,  while  in 
other  parts  of  the  Coastal  Plain  it  is  often  much  thicker. 

The  Sunderland  formation  contains  less  clay  loam  than  it  does  in 
other  parts  of  the  State  and  for  this  reason  the  upland  roads  which  are 
generally  located  on  the  Sunderland-covered  divides  are  so  sandy. 
The  clay  loam  of  the  Sunderland  constitutes  the  greater  portion  of  the 
Leonardtown  and  Norfolk  loams  whose  distribution  is  shown  on  the 
soil  map  of  the  county.  In  many  places  the  materials  mapped  as  loam 
are  entirely  too  sandy  for  the  manufacture  of  brick,  but  in  many  other 
places  in  these  areas  clay  suitable  for  common  brick  can  be  obtained. 
Where  the  clay  can  be  used  the  cost  of  removal  entails  only  a  slight 
expense  because  of  the  small  amount  of  stripping  required.  Similar 
clays,  utilized  in  Virginia  are  obtained  by  merely  removing  the  few 
inches  of  surface  material  which  is  filled  with  plant  roots. 

Beside  the  surface  clay  loams,  lenses  of  plastic  drab  clay  are  fre- 
quently found  near  the  base  of  the  Sunderland  deposits.  These  can  be 
seen  outcropping  in  many  places  on  the  steeper  slopes.  In  general, 
these  lenses  are  of  small  extent  but  some  are  sufficiently  thick  and 
extensive  to  be-  worked,  although  in  places  they  contain  considerable 
vegetable  material  which  renders  them  less  serviceable.  Clays  of  this 


126  THE    ECONOMIC    RESOURCES    OF    CALVERT    COUNTY 

character  are  well  exposed  in  the  Bay  cliffs  about  one-half  mile  north 
of  Point  of  Eocks. 

The  clays  of  the  Wicomico  formation  closely  resemble  those  of  the 
Sunderland  both  in  general  character  and  mode  of  occurrence.  The 
surface  loams  in  many  places  are  suitable  for  the  manufacture  of  a  fair 
quality  of  brick,  although  they  have  never  been  used  for  that  purpose 
in  the  county.  Elsewhere  in  the  State  and  in  adjoining  States  extensive 
brick  plants  obtain  their  material  from  the  surface  clay  loam  of  the 
Wicomico  formation.  In  a  general  way  the  areas  of  Sassafras  loam  shown 
on  the  soil  map  of  the  county  approximately  represent  the  development 
of  the  Wicomico  surface  loams.  It  must  be  borne  in  mind,  however, 
that  a  soil  map  and  a  geological  map  are  constructed  on  an  entirely 
different  basis  and  seldom  do  the  lines  defining  the  areas  of  certain  soils 
coincide  with  the  boundary  lines  of  the  geological  formations.  Some 
small  portions  of  the  Sassafras  loam  are  of  Sunderland  age  and  some 
belong  to  the  Miocene  yet  the  greater  part  represents  the  Wicomico 
surface  loam.  Further  small  portions  of  the  Wicomico  surface  loam 
are  mapped  as  meadow  soils  on  the  soil  map.  The  clay  lenses  of  the 
Wicomico  which  resemble  those  of  the  Sunderland  are  not  extensive 
enough  to  be  of  any  particular  importance. 

The  Talbot  is  the  only  formation  of  the  county  which  has  ever  fur- 
nished material  for  brick.  At  Rousby  on  the  mainland  opposite  Solo- 
mon's Island,  brick  was  formerly  made  from  the  Talbot  clay  loam,  which 
in  this  county  is  usually  of  superior  value  to  that  of  the  Wicomico  and 
Sunderland  formations.  These  Talbot  loam  areas  are  most  extensive 
along  the  Patuxent  Eiver  where  they  cover  the  low  flat  divides  between 
the  tributary  streams.  With  the  exception  of  the  valleys  of 
these  streams  the  meadow  soil  areas  of  the  soil  map  approximately  coin- 
cide with  the  distribution  of  the  Talbot  surface  clay  loam.  As  has  been 
demonstrated  by  the  plant  at  Rousby,  the  Talbot  loam  produces  a  fair 
quality  of  brick. 

Beside  the  surface  loam  of  the  Talbot,  there  are  several  other  deposits 
of  clay  present  in  this  formation  which  doubtless  have  some  value.  They 
consist  of  lenses  of  bluish-green  to  black  plastic  clay  which  have  been 


MARYLAND   GEOLOGICAL    SURVEY  127 

exposed  through  wave-cutting  along  the  Bay  and  the  Patuxent  River  in 
the  southern  portion  of  the  county.  They  are  seen  one-half  mile  north- 
east of  Drum  Point,  one-quarter  mile  west  of  Drum  Point,  and  one-half 
mile  south  of  St.  Leonard  Creek.  Similar  clays  occurring  at  Bodkin 
Point  near  the  mouth  of  the  Patapsco  River  have  been  tested  and  de- 
scribed by  Dr.  Heinrich  Ries.1  He  states  that  the  clay  "burned  to  a 
good  red  color  under  ordinary  conditions  and  to  a  deep  brown  when 
vitrified.  Before  this  clay  could  be  used  in  large  ware  it  would  be 
necessary  to  add  sand  to  prevent  excessive  shrinkage."  In  certain  out- 
crops these  clays  contain  sufficient  vegetable  material  to  render  them  unfit 
for  use  but  in  others  they  contain  very  little  organic  matter. 

THE  SANDS. 

Since  the  arenaceous  phase  predominates  in  almost  every  formation 
represented  in  the  region,  the  county  contains  an  unlimited  supply  of 
sand.  The  sand  of  the  Pleistocene  is  used  locally  for  building  purposes, 
but  since  it  is  so  readily  obtained  in  all  parts  of  the  county  no  pits  of 
any  considerable  size  have  been  opened.  It  is  said  to  be  a  fairly  good 
building  sand  yet  no  better  than  quantities  of  sands  in  other  parts  of  the 
State,  hence  the  demand  for  it  is  purely  local. 

In  some  places  the  quartz  sands  of  the  Miocene  seem  to  be  pure  enough 
for  glass-making,  suggesting  the  Miocene  glass  sands  so  extensively  ex- 
ploited in  southern  New  Jersey,  although  they  have  never  been  used  for 
that  purpose  in  this  region.  Careful  chemical  analyses  and  physical 
tests,  which  have  not  been  made,  would  be  required  to  determine  their 
usefulness  in  this  respect. 

Locally,  the  Pleistocene  sands  are  rich  in  ferruginous  matter  which, 
in  places,  cements  the  grains  together  forming  a  ferruginous  sandstone. 
Sands  of  this  character  possess  a  distinct  value  for  road-making  pur- 
poses, as  they  pack  readily  and  make  a  firm  road  bed.  Where  the 
material  can  be  easily  obtained  in  large  quantities  good  roads  of  this 
kind  can  be  very  economically  constructed.  The  ferruginous  sands  are 
best  developed  in  the  Sunderland  formation,  principally  because  of  the 

1Md.  Geol.  Survey,  vol.  iv,  1902. 


128  THE   ECONOMIC    RESOURCES   OF    CALVERT    COUNTY 

greater  age  of  the  deposits,  although  also  represented  in  the  Wicomico 
and  the  Talbot. 

THE  GRAVELS. 

The  Pleistocene  formations  contain  numerous  beds  of  gravel  widely 
distributed  throughout  the  region.  They  occur  in  pockets  or  lenses, 
either  immediately  at  the  surface  or  but  thinly  covered  by  the  sands  and 
loam.  In  the  latter  case  they  can  be  seen  in  many  places  outcropping 
along  the  valleys.  These  gravel  deposits  have  only  been  used  to  a  small 
extent  in  this  section  although  similar  deposits  in  the  vicinity  of  Wash- 
ington have  been  extensively  worked.  As  ballast  for  roads  they  possess 
considerable  value  and  will  doubtless  be  extensively  used  in  the  future 
in  the  building  of  permanent  roads  throughout  the  county.  They  are 
probably  inferior  in  value  to  the  igneous  rocks  yet  serve  their  purpose 
well  when  properly  used.  They  are  generally  rich  in  iron,  which  acts 
as  a  cementing  agent,  although  there  are  many  places  where  the  gravels 
lack  this  desirable  material.  In  such  cases  it  is  necessary  to  add  ferru- 
ginous sand  or  clay  to  bind  them  together.  The  most  extensive  surface 
gravel  deposits  are  located  near  Bowens  and  Ferry  Landing.  The  gravels 
range  in  size  from  coarse  sand  to  pebbles  several  inches  in  diameter. 

THE  BUILDING   STONE. 

Although  the  formations  of  the  county  are  composed  almost  entirely 
of  unconsolidated  materials,  yet  locally  indurated  beds  are  not  uncom- 
mon. In  the  absence  of  any  better  stone  these  indurated  ledges  furnish 
considerable  material  for  the  construction  of  foundations  and  well  walls. 
At  Mackall,  near  the  mouth  of  St.  Leonard  Creek,  there  is  a  firm  ledge 
of  Miocene  rock  which  has  been  utilized  for  such  purposes.  Elsewhere 
ferruginous  sandstones  and  conglomerates  from  the  Pleistocene  deposits 
supply  the  small  local  demand  for  rough  building  purposes. 

THE  MARLS. 

The  Eocene  and  Miocene  formations  of  the  State  are  rich  in  deposits 
of  marl  which  are  of  value  as  fertilizers.  From  New  Jersey  to  North 
Carolina  these  deposits  have  been  spasmodically  worked  since  the  early 


MARYLAND  GEOLOGICAL  SURVEY. 


CALVERT  COUNTY,   PLATE  X. 


FlG.    I. — VIEW   SHOWING   CLIFFS   OF  DIATOMACEOUS   EARTH,   LYONS   WHARF. 


FlG.    2. — VIEW  OF  DIATOMACEOUS  EARTH-PIT  OF  MARYLAND   SILICATE  COMPANY,  LYONS   WHARF. 


MAKYLAND   GEOLOGICAL    SURVEY  129 

part  of  the  last  century,  yet  their  importance  in  the  enrichment  of  the 
soil  has  never  been  generally  recognized.  At  present  their  use  in  Mary- 
land has  been  almost  entirely  discontinued  although  the  deposits  are 
practically  inexhaustible. 

The  Eocene  marls  are  glauconitic  in  character  and  constitute  the 
entire  thickness  of  the  Eocene  deposits  which  outcrop  in  the  north- 
western corner  of  the  county  along  Lyons  Creek  and  the  Patuxent  River. 
They  consist  of  quartz  sand  with  an  admixture  of  many  grains  of  glau- 
conite,  a  soft  green  mineral  which  is  essentially  a  hydrous  silicate  of 
iron  and  potassium.  On  account  of  the  glauconite,  the  marls  are  green 
in  color  and  are  commonly  known  as  "  greensand  marls."  They  are  also 
rich  in  calcium  carbonate,  derived  from  the  shells  which  are  abundant  in 
the  deposits,  and  chemical  analyses  usually  show  the  presence  of  small 
amounts  of  mineral  phosphates.  The  marls  thus  contain  three  important 
plant  foods — potash,  lime,  and  phosphates.  Altogether  these  form  only 
a  small  percentage  of  the  entire  content  of  the  marl,  yet,  wherever  the 
marls  can  be  obtained  at  low  cost,  they  furnish  economical  means  for 
increasing  soil  fertility.  In  New  Jersey,  Delaware,  and  the  Eastern 
Shore  of  Maryland  where  similar  marls  are  found  in  the  Cretaceous 
deposits,  they  have  been  extensively  worked  and  almost  everywhere  re- 
garded as  valuable  fertilizers,  it  being  claimed  that  the  beneficial  effect 
of  the  glauconitic  marl  is  much  more  lasting  than  that  obtained  by  the 
use  of  artificial  fertilizers.  The  method  of  application  is  to  scatter 
thinly  over  the  surface  during  the  winter  months  and  plow  under  the 
following  spring.  In  Calvert  County,  because  of  the  small  area  where 
these  marls  appear  at  the  surface,  they  can  never  be  of  any  great  value 
to  the  entire  county  but  might  be  profitably  used  in  the  vicinity  of  their 
outcrop. 

The  shell  marls  of  the  Miocene  also  possess  valuable  fertilizing  proper- 
ties for  soils  deficient  in  lime.  The  shell  beds  outcrop  almost  continu- 
ously in  the  cliffs  of  the  Bay  shore  and  are  encountered  along  the  valleys 
of  the  streams  tributary  to  Chesapeake  Bay  and  the  Patuxent  River 
throughout  the  greater  portion  of  the  county.  In  places  the  shells  are 


130  THE   ECONOMIC    RESOURCES   OF    CALVERT    COUNTY 

mixed  with  so  much  sand  that  the  lime  forms  only  a  small  percentage, 
but  in  other  places  the  amount  of  lime  exceeds  90  per  cent. 

The  value  of  the  shell  marls  and  methods  for  using  them  are  thor- 
oughly discussed  by  Professor  H.  J.  Patterson  in  a  Bulletin  of  the 
Maryland  Agricultural  Experiment  Station  (No.  66,  May,  1900).  He 
states  that  the  lime  has  an  especially  beneficial  effect  upon  sandy  soils, 
such  as  prevail  throughout  Calvert  County,  in  improving  their  physical 
characteristics.  This  it  does  through  its  cementing  action  which  ren- 
ders such  soils  less  porous  and  thus  enables  them  to  retain  moisture 
better.  Chemically,  lime  corrects  the  acidity  of  the  soils  through  its 
neutralizing  effect  upon  acids,  acting  upon  other  soil  constituents,  ren- 
dering them  available  for  plant  food,  and  finally  serves  as  a  plant  food 
itself.  Many  experiments  which  have  been  tried  in  various  places  all 
show  the  value  of  lime  as  a  fertilizer,  and  experiments  in  this  State  show 
that  better  results  were  obtained  by  the  use  of  shell  marl  than  with 
burned-stone  lime.  No  doubt,  any  of  the  soils  of  Calvert  County  might 
be  considerably  improved  at  small  expense  by  the  generous  use  of  shell 
marl,  deposits  of  which  are  readily  accessible  to  a  large  part  of  the 
county. 

THE  DIATOMACEOUS  EARTH. 

Diatomaceous  earth,  infusorial  earth,  or  tripoli  is  a  siliceous  deposit 
composed  mainly  of  the  microscopic  tests  of  diatoms,  a  low  order  of 
aquatic  plants.  The  material  is  soft,  porous,  light  in  weight,  and  very 
friable.  When  fresh  it  is  greenish  in  color  but  on  exposure  to  the  air 
the  color  changes  to  buff  or  almost  pure  white.  The  diatomaceous  earth 
occurs  in  the  lower  part  of  the  Calvert  formation  and  is  well  exposed  in 
many  places  along  the  Bay  and  river  shores  and  in  the  tributary  stream 
valleys  in  the  northern  half  of  the  county. 

The  diatomaceous  earth,  on  account  of  its  porosity  and  compactness, 
is  used  irf  water  niters.  It  is  reduced  readily  to  a  fine  powder  and  makes 
an  excellent  base  for  polishing  powders.  On  account  of  its  porous 
nature,  diatomaceous  earth  is  used  as  an  absorbent  in  the  manufacture 
of  dynamite,  while  its  non-conductivity  of  heat  makes  it  a  valuable  in- 
gredient in  packing  for  steam  boilers  and  pipes,  and  in  safes.  This 


MARYLAND   GEOLOGICAL   SURVEY  131 

latter  is  the  principal  use  to  which  it  is  put.  It  has  been  thought  that 
the  diatomaceous  earth  might  be  of  use  in  certain  branches  of  pottery 
manufacture,  which  require  on  the  part  of  the  materials  refractoriness 
and  an  absence  of  color  when  burned.  Dr.  Heinrich  Eies  tested  a  sample 
of  the  diatomaceous  earth  from  Lyons  Creek  at  cone  27  in  the  Deville 
furnace  and  found  that  the  material  fused  to  a  drop  of  brownish  glass. 
The  non-refractory  character  of  the  diatomaceous  earth  is  thus  clearly 
demonstrated.  It  is  also  used  in  the  manufacture  of  fire  and  heat- 
retarding  cements  and  fire-proof  building  materials,  such  as  solid  brick 
and  hollow  brick  for  partition  walls  and  floors. 

Not  all  of  the  diatomaceous  earth  of  the  region  is  valuable,  some  con- 
taining an  excessive  amount  of  sand.  At  Lyons  Creek  wharf  it  is  quite 
pure  and  has  been  worked  for  a  number  of  years  by  the  Maryland  Sili- 
cate Company.  The  deposit  is  about  20  feet  in  thickness  at  this  point. 
The  output  of  the  Lyons  Creek  locality  long  exceeded  that  of  any  other 
region  in  the  United  States  and  put  Maryland  at  the  head  of  the  diato- 
maceous-earth  producing  states.  The  average  value  is  about  $5000.  It 
varies  greatly,  however,  in  different  years  because  of  the  varying  demand 
for  the  material,  and  partly  because  of  the  production  of  a  supply  in 
some  years  sufficient  to  meet  the  trade  demand  for  several  years  in 
advance.  Because  of  the  limited  demand  for  it  and  the  considerable 
number  of  states  in  which  diatomaceous  earth  is  found  it  is  improbable 
that  the  industry  in  Calvert  County  will  ever  reach  very  large  proportions. 

THE  WATER  RESOURCES. 

The  available  water  resources  of  Calvert  County  include  the  surface 
streams,  natural  springs,  and  the  dug  or  driven  wells.  In  the  absence  of 
large  towns  or  great  industries  where  large  amounts  of  water  are  re- 
quired, the  streams  have  not  been  utilized  for  water-supply  purposes. 
In  fact,  it  is  doubtful  if  they  could  ever  be  depended  upon  for  potable 
water  because  of  the  large  amount  of  vegetation  which  they  contain 
during  the  summer  months  and  the  liability  to  contamination  from  the 
run  off  of  the  adjoining  cultivated  lands.  In  some  instances  dams  have 
been  constructed  and  the  power  utilized  by  small  manufacturing  con- 


132  THE   ECONOMIC    RESOURCES    OF    CALVERT    COUNTY 

cerns,  but  because  of  the  gentle  slope  of  all  except  the  smallest  streams 
the  amount  of  water-power  developed  is  very  slight. 

SPRINGS. — The  nature  of  the  topography  of  the  region  with  many 
stream-valleys  cut  almost  to  sea  level  combined  with  the  gentle  dip  of  the 
different  beds  of  varying  permeability  afford  excellent  conditions  for  the 
development  of  springs.  The  ground  water  sinking  through  the  porous 
Pleistocene  deposits  until  the  less  porous  beds  of  the  Miocene  are  en- 
countered, flows  along  the  contact  until  it  is  tapped  by  some  valley 
elope  where  it  issues  as  a  line  of  seepage  or  as  a  spring.  A  large  per- 
centage of  the  ground  water  is  not  checked  at  the  contact  of  the  Pleisto- 
cene and  Miocene  but  passes  downward  through  the  sandy  layers  of  the 
latter  formation  until  its  further  progress  is  checked  by  more  argillaceous 
beds  along  which  it  flows  until  the  layer  outcrops  at  the  surface.  The 
more  deep-seated  springs  of  the  latter  sort  which  penetrate  Miocene  beds 
are  apt  to  be  purer  than  the  shallow  springs  and  furnish  an  unfailing 
supply  of  excellent  water.  In  addition  to  the  increased  danger  of  con- 
tamination in  the  shallower  springs,  they  are  very  apt  to  fail  in  dry 
weather. 

While  the  spring  water  is  sometimes  charged  with  iron  derived  in  the 
main  from  the  Pleistocene  deposits,  it  is  as  a  rule  remarkably  free  from 
mineral  matter  of  all  kinds. 

DUG  WELLS. — Except  on  the  top  of  narrow  divides  between  deep  valleys, 
the  ground  water  level  lies  near  the  surface  and  abundance  of  water  can 
be  obtained  from  dug  wells  of  shallow  depth.  On  the  narrow  divides, 
however,  the  water  table  in  the  dry  months  of  the  year  lies  only  a  little 
above  sea  level,  thus  necessitating  the  sinking  of  wells  almost  to  that 
plane  in  order  to  obtain  a  permanent  supply  of  water.  The  highest 
divides  in  the  county  rise  to  an  elevation  of  about  180  feet  and  in  a  few 
instances  it  has  been  necessary  to  sink  wells  to  almost  that  depth  to 
secure  plenty  of  water  during  all  seasons  of  the  year.  On  the  broad, 
low-lying  flats  bordering  the  Patuxent  Eiver,  on  the  other  hand,  it  is 
seldom  that  the  wells  exceed  20  feet  in  depth  and  sometimes  the  water 
rises  to  the  surface.  In  general  the  water  in  these  most  shallow  wells 


MARYLAND   GEOLOGICAL    SURVEY  133 

is  much  more  apt  to  be  impure,  although  in  many  places  it  is  used 
exclusively  without  any  apparent  injurious  effects. 

ARTESIAN  WELLS. — As  good  water  in  sufficient  quantity  can  be  ob- 
tained almost  everywhere  in  the  county  at  moderate  depths  few  attempts 
have  been  made  to  obtain  artesian  water.  Borings  that  have  been  made, 
however,  show  that  artesian  water  underlies  practically  the  entire  county. 
Plowing  wells  have  been  secured  on  the  low-lying  land  bordering  Chesa- 
peake Bay  and  the  Patuxent  Kiver,  but  it  is  very  doubtful  whether  they 
can  be  secured  at  any  point  in  the  county  with  an  elevation  exceeding 
20  feet  above  sea  level.  The  water  obtained  in  the  artesian  wells  usually 
contains  some  mineral  matter  in  solution  but  not  sufficient  to  interfere 
with  its  use  for  most  purposes.  Free  from  surface  contamination,  it  is 
the  most  healthful  water  of  the  region. 

There  seems  to  be  two  distinct  water  horizons  that  furnish  the  supply 
in  the  artesian  wells  thus  far  bored.  One  of  these  is  found  in  the  upper 
portion  of  the  Cretaceous,  probably  within  the  Magothy  formation,  while 
the  other  is  located  near  the  base  of  the  Calvert  formation. 

The  Magathy  ( ?}  Horizon. — The  only  artesian  well  in  the  county 
that  derives  its  water  from  the  upper  Cretaceous  is  the  295-foot  well  at 
Chesapeake  Beach.  The  water  is  of  good  quality  and  yields  about  six 
gallons  per  minute.  This  seems  to  be  the  same  horizon  which  has  been 
penetrated  by  the  flowing  wells  at  Upper  Marlboro  at  a  depth  of  about 
225  feet. 

In  the  northern  part  of  the  county  the  Magothy  horizon  is  the  only 
one  that  lies  near  enough  to  the  surface  to  be  reached  at  moderate  depths. 
Since  all  the  Coastal  Plain  formations  dip  to  the  southeast  beneath  pro- 
gressively younger  deposits,  presumably  the  artesian  water-bearing  hori- 
zons of  the  Potomac  formations  which  supply  the  water  for  many 
artesian  wells  near  Washington  and  Baltimore,  underlie  Calvert  County. 
They  are,  however,  so  deeply  buried  that  only  the  demand  for  an  unusu- 
ally large  supply  of  water  would  warrant  seeking  artesian  water  from 
these  strata  in  Calvert  County,  since  the  Magothy  horizon  seems  to  be 
sufficient  for  present  needs.  In  the  central  and  southern  portions  of  the 
county  where  another  artesian  water-bearing  horizon  lies  nearer  the 


134  THE   ECONOMIC    EESOUECES   OF    CALVERT   COUNTY 

surface  the  borings  have  not  extended  to  the  Magothy  horizon  so  that 
it  is  not  known  at  what  depth  it  could  be  reached  there. 

The  Calvert  Horizon. — The  remaining  artesian  wells  of  the  county 
derive  their  water  supply  from  near  the  base  of  the  Calvert  formation. 
It  is  not  believed  that  they  all  draw  their  supplies  of  water  from 
exactly  the  same  horizon  but  that  they  tap  numerous  water-bearing 
strata  located  at  various  depths  within  the  formation.  It. is  also  pos- 
sible that  the  Governor  Eun  well  penetrates  the  Eocene  a  short  distance. 
Because  of  the  rapid  thinning  of  the  Miocene  deposits  northwestward 
only  the  southern  half  of  the  county  is  underlain  by  the  Calvert  water 
horizon.  It  furnishes  the  water  in  the  wells  at  Eousby  and  Solomon's 
Island,  and  probably  that  at  Governor  Run.  The  well  at  Eousby  is  240 
feet  deep  and  furnishes  a  large  supply  of  fine  water.  There  are  four 
wells  on  Solomon's  Island  ranging  in  depth  from  252  to  258  feet.  These 
wells  possess  a  good  flow,  which  is  somewhat  greater  at  high  tide  than 
at  low.  The  water  when  first  drawn  tastes  and  has  the  odor  of  marsh 
mud  but  this  disappears  upon  exposure. 

Beside  these  wells  in  Calvert  County  there  are  others  just  across  the 
river  in  St.  Mary's  County  which  show  the  general  artesian-water  condi- 
tions of  the  region.  At  Millstone,  artesian  water  is  reached  at  290 
feet;  at  Pearson  mineral  water  is  obtained  at  257  feet;  while  at  Sotterly 
artesian  water  is  obtained  at  225  feet. 


THE  SOILS  OF  CALVERT  COUNTY 

BY 

JAY  A.  BONSTEEL  AND  R.  T.  AVON  BURKE 


INTRODUCTORY. 

Calvert  County,  Maryland,  comprises  an  area  of  218  square  miles 
lying  between  the  Patuxent  Eiver  and  the  Chesapeake  Bay.  It  is  the 
smallest  county  in  Maryland.  The  extreme  length  of  the  county  from 
northwest  to  southeast  is  slightly  over  35  miles,  and  it  varies  in  breadth 
from  9  miles  in  the  northern  part  of  the  area  to  about  5  miles  in  the 
southern  part.  The  entire  area  of  the  county  is  included  between  the 
parallels  of  38°  20'  to  38°  45'  north  latitude  and  the  meridians  of 
76°  22'  to  76°  41'  west  longitude.  The  extreme  elevation  of  the  county 
above  sea  level  is  less  than  200  feet.  Its  long  coast  line  and  the  numerous 
embayments  along  the  Patuxent  shore  make  the  county  easily  accessible 
by  water.  Prince  Frederick  is  the  county  seat  and  Solomons  its  largest 
town.  Agriculture  and  the  oyster  industry  are  the  chief  occupations  of 
its  inhabitants. 

THE  PHYSICAL  GEOGRAPHY. 

Calvert  County  extends  as  a  long,  narrow  peninsula,  between  two  tide- 
water estuaries,  and,  while  half  of  its  area  rises  to  120  feet  elevation 
or  higher,  the  surface  is  very  uneven  and  very  much  cut  up  by  streams. 
This  is  due  to  the  steep,  short  fall  of  the  water  courses  and  to  the 
unconsolidated  nature  of  the  materials  upon  which  the  water  acts. 

Hunting  Creek,  flowing  into  the  Patuxent,  and  Fishing  Creek, 
flowing  into  Chesapeake  Bay,  have  nearly  cut  the  county  into  two 
parts.  Battle  Creek  and  Parker  Creek  have  almost  accomplished  the 
same  dissection  farther  south,  while  St.  Leonard  Creek  has  its  head- 
waters within  a  half  mile  of  Chesapeake  Bay,  though  flowing  into  the 
Patuxent.  Many  smaller  streams  have  also  deeply  trenched  the  surface. 


136  THE   SOILS    OF    CALVERT    COUNTY 

As  a  consequence  of  this  active  stream  erosion  the  greater  part  of 
the  county  consists  of  steep-sided,  flat-topped  hills  and  long,  narrow 
necks  of  upland  country. 

Along  the  greater  part  of  the  Patuxent  a  narrow,  flat-topped  fore- 
land is  found  between  the  upland  slope  and  the  water.  In  the  vicinity 
of  Solomons  Island  and  St.  Leonard  Creek  this  foreland 
has  a  breadth  of  about  two  miles  and  its  surface  lies  at  an  elevation  of 
between  20  and  40  feet  above  tide.  Between  St.  Leonard  Creek  and 
Sheridan  Point  the  foreland  is  narrower  and  more  sloping,  while  from 
Sheridan  Point  to  Deep  Landing  it  is  very  broad  and  flat.  Above 
Deep  Landing  the  foreland  terrace  rises  in  elevation  to  a  maximum 
of  over  80  feet  at  Lyons  Creek  Wharf  and  it  varies  greatly  in  elevation, 
extent,  and  in  soil  types  in  this  northern  portion  of  its  extent. 

The  streams  of  any  size  in  Calvert  County  flow  into  the  Patuxent 
Eiver  with  but  two  exceptions — Parker  Creek  and  Fishing  Creek.  This 
fact,  considered  in  connection  with  the  general  presence  of  forelands 
along  the  Patuxent  and  their  absence  along  the  Bay,  bears  testimony 
to  long-continued  wave-cutting  on  the  Bay  shore,  resulting  in  the  de- 
struction of  formerly  existing  forelands  as  well  as  causing  large  and 
continued  inroads  upon  the  main  upland. 

The  streams  which  flow  into  the  Patuxent  Eiver  constitute  the  major 
part  of  the  drainage  area  of  the  county.  Their  head-waters  are  uni- 
formly found  near  the  Chesapeake  Bay  shore  line  and  they  flow  south  or 
southwest  into  estuaries  of  the  Patuxent.  The  valley  walls  are  uniformly 
steep  and  poorly  adapted  to  cultivation;  while  the  stream  bottoms  are 
usually  narrow,  flat,  and  wet,  adapted  to  pasturage  more  than  to  any  other 
agricultural  use. 

Along  the  lower  courses  of  the  larger  streams  there  are  found  some 
notable  exceptions  to  the  general  rule  of  steep,  sloping,  wooded  valley 
walls.  Beginning  just  above  where  the  stream  proper  empties  into  its 
tidewater  estuarine  portion  are  low-lying,  flat-topped  terraces,  rising 
to  an  elevation  of  from  40  to  60  feet.  If  the  surface  of  these  terraces 
or  terrace  remnants  is  followed  toward  the  Patuxent  Eiver,  it  will  be 
found  to  descend  to  slightly  lower  elevations  and  finally  in  many  in- 


MARYLAND   GEOLOGICAL    SURVEY  137 

stances  it  is  continued  along  the  Patuxent  itself  by  the  foreland  areas 
already  described.  In  fact  the  foreland  is  merely  a  similar  terrace 
formed  along  the  Patuxent. 

From  an  agricultural  standpoint  the  facts  of  physical  geography  are 
of  greatest  interest  in  connection  with  the  results  produced  on  the 
land  surface.  As  a  brief  summary  of  the  effects  upon  Calvert  County 
it  may  be  stated,  that  the  continual  action  of  storm  waves  along  the 
bay  shore  will  steadily  though  slowly  cut  away  the  land  area  at 
exposed  points  and  deposit  this  material  as  sand  bars  and  mud-flats 
where  sheltered  positions  or  cross  currents  cause  a  slack  water  area. 
The  equally  continuous  erosion  performed  by  the  head-waters  of  all 
streams  will  wear  away  the  upland  surface  and  transport  the  derived 
materials  to  tide  water  estuaries  where  they  will  be  deposited,  forming 
mud-flats  and  marshes  and  causing  a  general  shallowing  of  all  adjoining 
water  courses,  except  where  tide  and  stream  currents  are  strong  enough 
to  keep  the  channels  open. 

Thus  upland  areas,  subject  to  rapid  rain  wash,  must  be  carefully 
tended,  while  the  wearing  away  of  the  Bay  shore  and  the  silting  up 
of  bays  along  the  Patuxent  are  inevitable  and  affect  both  agriculture  and 
agricultural  transportation. 

THE   GEOLOGY. 

Calvert  County  lies  entirely  within  the  Coastal  Plain  division  of 
Marjland,  and  the  geologic  formations  which  enter  into  its  structure  are 
composed  of  unconsolidated  clays,  sands,  and  gravels,  together  with 
remains  of  organic  life  like  the  diatomaceous  earths  and  the  marl  bods. 
These  materials,  though  unconsolidated,  form  rocks  in  the  geologic 
sense,  since  they  constitute  an  integral  part  of  the  earth's  crust.  They 
are  still  passing  through  the  earlier  stages  of  rock  formation,  and  neither 
pressure  nor  cementation  has  progressed  far  enough  to  bind  the  inco- 
herent masses  into  firm,  solid  rocks. 

All  geologic  formations  of  sedimentary  origin  are  divided  and  sub- 
divided into  various  groupings  according  to  their  age,  as  determined  by 
the  character  of  the  fossil  organisms  entombed  in  them,  and  according 
10 


138 


THE   SOILS    OF    CALVERT    COUNTY 


to  the  sequence  of  the  formations.  Thus  the  grand  divisions  of  Archaean, 
Algonkian,  Paleozoic,  Mesozoic,  and  Cenozoic  are  sub-divided  again 
and  again.  Only  strata  of  the  Cenozoic  age  are  represented  in  Calvert 
County,  so  only  their  sub-divisions  will  be  considered. 


Group. 


r Pleistocene.  . .  .Columbia. 


Formation. 


Soil  type. 


Cenozoic. . .  . 


Talbot 3  Meadow  soil. 

j  Sassafras  sandy  loam. 


Miocene Chesapeake. 


Wicomico.  .  . 


-Sunderland . 


St.  Mary's.  . 
Choptank .  .  . 


Norfolk  sand. 
Sassafras  loam. 

T  Norfolk  loam. 

Leonardtown  loam. 
••I  Susquehanna  gravel. 

Windsor  sand. 
[  Norfolk  sand. 

.     No  soil  areas. 

Windsor  sand. 
Norfolk  sand. 


Calvert J  Sassafra 

Basal  clays. 


Eocene Pamunkey j  Nanjemoy No  soil  areas. 

|  Aquia No  soil  areas. 


The  oldest  strata  found  belong  to  the  Pamunkey  Group  of  the  Eocene. 
They  consist  of  greensands,  which  outcrop  along  the  Patuxent  Elver 
and  its  tributaries  from  the  vicinity  of  Ferry  Landing  northward  to 
the  county  line.  They  reach  the  surface  as  outcrops  which  form  no 
surface  features  and  no  soils.  Over  this  group  is  found  the  Chesa- 
peake (of  Miocene  age)  which  is  sub-divided  into  three  formations.  The 
lowest,  the  Calvert,  occurs  at  the  surface  in  the  form  of  a  modified  type  of 
Sassafras  loam.  For  the  most  part  its  chief  role  is  to  form  the  basal 
structure  upholding  the  soil  proper  of  the  county. 

The  next  formation,  the  Choptank,  is  composed  of  fine  and  medium- 
grained  sands  and  contains  marl  beds.  The  surface  exposures  con- 
tribute to  the  Windsor  sand  and  form  the  main  part  of  the  Norfolk  sand. 
Above  the  Choptank  occur  the  St.  Mary's  strata,  which  form  no  extensive 
surface  feature  and  thus  give  rise  to  no  soil  type. 


MARYLAND    GEOLOGICAL    SURVEY  139 

It  will  be  seen  from  the  table  above  that  the  Eocene  has  no  soil 
equivalent,  because  buried  too  deeply  under  more  recent  material.  Even 
the  Miocene,  with  its  three  formations,  plays  but  small  part  in  the  soils 
of  the  present  time.  Almost  the  entire  land  surface  is  derived  from 
the  three  formations  of  the  Columbia  Group  of  the  Pleistocene  period. 
These  three  divisions  are  the  Sunderland,  the  Wicomico,  and  the  Talbot — • 
named  in  the  order  of  their  deposition. 

The  oldest  formation,  the  Sunderland,  exists  as  an  almost  continuous 
sheet  of  gravel,  clay,  and  loam,  covering  the  highest  upland  portions 
of  the  county.  According  as  the  component  materials  differ  in  texture 
and  structure,  depending  upon  the  origin  of  the  material  and  upon 
the  methods  and  conditions  of  its  deposition,  it  gives  rise  to  the  Norfolk 
loam,  the  Leonardtown  loam,  the  Susquehanna  gravel,  the  Windsor 
sand,  and  the  Norfolk  sand.  The  last  two  of  these  soils  occur  also 
as  derivatives  from  the  Choptank  formation  of  the  Chesapeake  Group. 

The  Wicomico,  which  occurs  as  a  fairly  well-defined  terrace  along 
the  Patuxent  and  its  tributaries,  gives  rise  to  the  Sassasfras  loam  over 
the  main  terraces  and  occasionally  to  small  areas  of  Norfolk  sand,  where 
these  terraces  are  continued  inland  along  the  larger  streams. 

The  latest  formed  Talbot  terrace  presents  two  characteristic  soil 
types — the  meadow  areas  of  the  foreland  and  the  Sassafras  sandy  loam. 

It  will  be  noticed  that  several  of  the  geological  formations  give  rise 
to  two  or  more  soil  types,  and  that  some  of  the  soil  types  are  derived 
from  two  or  more  geological  formations.  This  emphasizes  the  fact 
already  noted  that  the  geological  classification  of  sedimentary  rocks  is 
based  upon  the  time  when  the  material  was  deposited ;  that  is,  upon 
the  relative  age  as  shown  by  the  stage  of  development  of  life1  forms 
rather  than  upon  the  character  of  the  materials.  The  soil  classification, 
on  the  other  hand,  is  based  upon  the  character  of  the  material  without 
regard  to  its  age. 

There  are  several  interesting  problems  regarding  the  origin  and 
deposition  of  the  Pleistocene  deposits.  The  beginning  of  the  Pleistocene 
stage  of  deposition  was  marked  in  Calvert  County  by  the  contribution 
of  rather  coarse  sand  and  gravel,  containing  some  boulders  of  such 


140  THE   SOILS    OF    CALVERT    COUNTY 

large  size  that  flowing  water  alone  could  not  carry  them.  They  could 
have  been  brought  to  their  present  location  only  as  debris  frozen  into 
or  borne  upon  the  surface  of  floating  ice.  Some  of  these  boulders 
are  very  interesting,  as  they  show  the  sources  of  the  material,  and 
consequently  give  some  idea  of  the  land  area  existing  at  the  time  of 
their  deposition.  Along  Hunting  Creek  a  boulder  was  found  which 
came  from  the  granite  area  near  Ellicott  City.  It  possessed  the  same 
peculiar  texture  as  that  granite — the  large  pink  feldspar  crystals  sur- 
rounded by  smaller-sized  crystals  of  other  component  minerals.  There 
are  also  found  boulders  of  other  rocks,  notably  gabbro  diorite,  a  dark 
green  or  black  rock  derived  from  the  same  general  region.  The  pres- 
ence of  these  boulders  not  only  gives  some  idea  of  the  land  surface 
existing  in  this  former  geologic  period,  but  their  transportation  by 
ice  also  gives  some  idea  of  the  climatic  conditions  then  existing.  The 
layer  of  material  bearing  these  boulders,  when  now  exposed,  gives  rise 
to  the  Susquehanna  gravel. 

After  the  deposition  of  this  gravelly  layer,  clay  and  silt  were  brought 
in.  The  peculiar  structure  of  the  subsoil  of  the  Leonardtown  loam 
is  clue  to  the  form  this  deposition  took  in  its  earlier  stages.  Clay 
pebbles  and  clay  boulders,  probably  derived  from  a  shore  line  by  wave 
action,  were  rolled  together  as  the  first  deposit  over  the  gravel  and 
interbedded  with  sand  and  some  small  gravel.  When  these  were  firmly 
packed  down  by  the  weight  of  accumulating  sediments  the  clay  pebbles 
were  flattened  out  into  lense-shaped  nodules,  and  the  resulting  soil 
structure  produces  the  effect  of  a  heavy  clay  subsoil  with  sandy  partings. 
This  feature  and  its  results  are  described  under  the  Leonardtown  loam 
soil  type. 

The  Leonardtown  loam  deposit  was  succeeded  by  silty  and  sandy 
materials,  giving  rise  to  the  Norfolk  loam.  After  this  the  entire  area 
was  slowly  elevated  above  water  level  and  stream  drainage  was  estab- 
lished over  the  newly  formed  surface.  In  many  cases  these  streams 
closely  followed  the  stream  beds  occupied  during  Miocene  times,  as 
these  were  only  partly  filled  in  during  the  Pleistocene  submersion.  As 
erosion  began  again  the  newly  deposited  materials  were  removed,  to- 


MARYLAND   GEOLOGICAL    SURVEY  141 

gether  with  older  Miocene  strata  as  they  were  reached  by  stream  cutting, 
and  terraces  were  built  near  the  mouths  of  the  new  streams,  while 
other  deposits  were  made  in  the  larger  drainage  systems  like  the 
Patuxent  Eiver.  As  the  gradual  elevation  of  the  land  proceeded  the 
erosion  and  deposition  continued  and  the  terraces  of  Wicomico  age, 
whose  fragmentary  remains  are  found  still  clinging  along  the  Chesapeake 
and  Patuxent  shores  and  recognized  as  Sassafras  loam  soils,  were  formed. 
As  the  latest  stage  of  this  action  the  foreland  areas  of  the  county,  the 
Sassafras  sandy  loam  and  meadow  soil,  were  formed  during  the  Talbot 
stage.  These  low-lying  terraces  were  constructed  along  the  Patuxent 
and  probably  also  along  the  Chesapeake,  though  subsequent  wave  action 
has  largely  destroyed  the  latter.  At  this  time  the  deeper  waters  were 
receiving  clayey  materials  and  the  shallower  ones  sand  and  silt.  This 
area  is  slowly  sinking  again  with  most  of  the  Atlantic  coast,  though 
the  motion  can  be  detected  only  by  careful  observations  extending  over 
long  periods  of  time.  The  usual  processes  of  weathering,  erosion,  trans- 
portation, and  deposition  are  in  progress,  and  strata  are  now  being 
formed  which  succeeding  ages  may  sometime  have  an  opportunity  to 
study  and  classify. 

The  soils  have  about  the  following  areas : 

AREAS  OF  THE  DIFFERENT  SOILS. 


Soils.  Acres.  Per  cent. 

Norfolk    sand    58,800  42 

Windsor    sand     24,500  18 

Meadow     15,800  11 

Sassafras  sandy  loam . . .  10,900  8 

Sassafras  loam    8,850  6 


Soils.  Acres.  Per  cent. 

Leonardtown    loam     ....    7,950  6 

Norfolk    loam     5,220  4 

Susquehanna    gravel    . . .   3,900  3 

Swamp    3,600  2 


THE  SOIL  TYPES. 
The  Norfolk  Loam. 

The  Norfolk  loam  is  found  in  irregularly-shaped  areas  on  the 
highest  uplands  near  Port  Eepublic,  Prince  Frederick,  and  Mt.  Har- 
mony. These  scattered  tracts  represent  an  area  which  must  have  been 


142  THE   SOILS    OF    CALVERT    COUXTT 

much  greater  at  some  former  time,  but  which  has  been  largely  removed 
by  active  stream  erosion,  still  continued. 

The  areas  as  they  exist  to-day  form  flat-topped  or  gently  undulating 
divides  between  stream  courses.,  sloping  away  on  all  sides  toward  the 
stream  valleys.  They  are  frequently  bordered  by  exposures  of  the 
barren  clay  subsoil  of  the  formation,  which  is  being  washed  away  by 
the  heavier  rain  storms  with  such  rapidity  that  vegetation  is  unable 
to  maintain  itself.  In  many  cases  the  clay  scald  thus  formed  descends 
to  a  ledge  of  iron-cemented  sand  and  gravel  or  to  a  distinct  gravel 
bed.  Such  an  occurrence  can  be  found  about  one  mile  south  of  Prince 
Frederick  along  the  main  highway. 

The  soil  owes  its  origin  to  the  deposition  of  a  fine  sandy  and  silty 
sediment  in  this  region  at  a  time  when  it  formed  a  portion  of  the  sea 
bottom,  and  to  the  subsequent  elevation  of  that  sea  bottom  above  tide 
level  followed  by  the  usual  processes  of  weathering  which  prepare  all 
soils  for  plant  growth. 

The  soil  itself  consists  of  a  fine  sandy  to  silty  loam  having  an  average 
depth  of  about  ten  inches.  It  usually  contains  some  organic  matter 
as  the  result  of  cultivation,  fallowing,  and  fertilizing.  The  subsoil  is 
a  heavier  sandy  yellow  loam  or,  in  some  cases,  a  yellow  loam.  It  varies 
in  thickness  from  about  twenty  inches  to  over  three  feet. 

It  is  usually  cultivated  over  the  entire  area  where  it  occurs, 
so  that  all  natural  tree  growth  has  been  removed.  Corn  produces  a 
good  crop,  and  it  was  a  noticeable  fact  that  during  the 
exceptionally  dry  months  of  August  and  September,  1900,  the  corn 
crops  on  this  soil  were  among  the  last  to  suffer.  Wheat  is  also  raised 
on  this  soil  and,  while  it  is  as  well  fitted  for  wheat  culture  as  the 
larger  part  of  the  soils  of  the  county,  it  is  not  a  typical  wheat  soil. 
On  the  other  hand  tobacco  does  well  upon  this,  both  as  regards  the 
quality  and  the  quantity  of  the  crop.  The  Norfolk  loam  is  probably 
the  best  general  purpose  soil  lying  in  the  upland  portion  of  the  county. 

The  following  analyses  show  the  texture  of  the  soil  and  the  subsoil  of 
this  formation. 


MARYLAND   GEOLOGICAL    SURVEY 


143 


MECHANICAL  ANALYSES  OF  NORFOLK  LOAM. 


•o 

c 

3 

o 

3 

2 

g 

~ 

* 

| 

5 

s 

. 

1 

1 

s 

~% 

0 

^rJ 

c's  :°.a 

II 

£  . 

s  . 

No. 

Locality. 

Description. 

So 

5  | 

g^  i  •§  a 

-'5 

0  1 

§a 

Gj"* 

~ 

w 

Sg  ,  So 

«° 

c> 

<s 

1 

a 

1 

i 

<o 
a 

&~ 

jj 

i 

O 

O 

CJ 

s 

&* 

>• 

s 

o 

5159 

Imile  NW.of  Port 
.Republic. 

Yellow,  sandy 
loam,  0  to   9 

P.ct. 
2.59 

P.ct. 
1.28 

P.ct. 

7.62 

P.ct. 

5.87 

P.ct. 
6.48 

P.ct. 
14.41 

P.ct. 
51.99 

P.ct. 
9.79 

inches. 

6160 

Subsoil  of  6169  

Heavy,  yellow 
loam,  9  to  30 

2.40 

1.02 

6.15 

6.36 

6.67 

10.32 

50.71 

18.19 

inches. 

The  Leonardtown  Loam. 

The  Leonardtown  loam  is  a  type  of  soil  found  extensively  in  St. 
Mary's  County,  and  named  from  the  county  seat.  In  Calvert  County 
the  type  constitutes  the  upland  in  the  forest  country  between  Drum  Point 
and  St.  Leonard  Creek,  though  many  small  areas  of  this  soil  occur  over 
the  uplands  farther  north.  Like  the  Norfolk  loam  only  a  small  portion 
of  the  original  extent  remains,  the  greater  portion  having  been  removed 
by  the  universal  erosion. 

The  surface  of  the  Leonardtown  loam  forms  a  part  of  the  nearly 
flat  but  gently  sloping  upland,  and  in  any  single  area  it  is  nearly  hori- 
zontal or  only  slightly  rolling. 

The  individual  tracts  in  the  southern  part  of  the  county  frequently 
contain  about  one  thousand  acres  of  very  uniform  soil,  while  the 
areas  farther  north  are  much  smaller — some  of  them  comprising  only  a 
few  acres  of  almost  barren  clay  subsoil — for  erosion  has  progressed  to 
such  an  extent  that  only  small  remnants  survive.  In  many  instances 
these  remnants  furnish  no  soil  of  agricultural  value,  but  they  are  occa- 
sionally selected  as  building  spots,  because  their  slight  elevation  above 
the  general  level  of  the  country  gives  good  drainage  facilities. 

The  Leonardtown  loam  owes  its  origin  to  the  deposition  of  clayey 
sediments  on  the  bottom  of  an  old  estuary  or  marine  area.  This  depo- 
sition over  a  large  portion  of  the  area  did  not  take  place  in  the  usual 
method — by  a  mechanical  settling  of  fine  sediment  from  suspension 


144  THE   SOILS   OF    CALVERT    COUNTY 

in  water.  Such  a  course  gives  rise  to  continuous,  homogeneous  layers 
of  clay,  while  the  Leonardtown  loam — where  undisturbed  by  cultivation 
and  by  the  action  of  frost,  rain,  and  other  atmospheric  agencies — 
presents  the  appearance  of  an  accumulation  of  clay  lenses  or  nodules, 
imperfectly  separated  from  each  other  by  veins  and  pockets  of  sand 
interspersed  with  scattered  pebbles. 

A  visit  to  the  present  cliff  line  of  Chesapeake  Bay  in  Calvert  County 
will  give  some  idea  of  the  manner  in  which  the  clay  lenses  of  the 
Leonardtown  loam  were  formed.  Wherever  the  waves  are  at  present 
cutting  on  clay  layers  steep  cliffs  are  formed,  and  the  continual  wearing 
near  tide  level  undermines  large  masses  of  clay  which  fall  down  within 
reach  of  the  waves,  where  they  are  further  broken  up  into  boulders  and 
pebbles  or  ultimately  reduced  to  a  fine  mud.  The  mud  is  generally 
washed  away  to  some  distance  and  only  settles  to  the  bottom  in  com- 
paratively still  water,  while  the  pebbles  and  boulders  of  clay  are  rolled 
on  the  bottom  of  the  bay  through  accumulations  of  sand  and  mud  and 
finally  come  to  rest,  unless  completely  broken  up,  as  a  pavement  of 
clay  lumps  interspersed  with  finer  materials.  The  waters  of  Chesa- 
peake Bay  are  so  shallow  at  present  that  only  small  portions  of  its 
bottom  lie  below  the  zone  of  wave  action,  especially  during  the  more 
severe  storms.  As  a  result  the  clays  are  usually  broken  up  very 
completely  and  only  the  finer  sediments  are  deposited.  Still  enough 
of  the  boulders  and  pebbles  survive,  even  along  the  shore,  to  give  an 
idea  of  the  general  operation  of  wave  forces  and  of  the  deposition 
resulting  from  such  action.  If  the  waters  of  the  bay  were  deeper, 
the  shoreward  slopes  more  shelving,  and  the  materials  worked  upon 
more  resistant  to  wave  action,  it  is  easy  to  see  that  the  result  would  be 
a  quite  general  deposition  of  beds  of  clay  pebbles. 

The  Leonardtown  loam,  over  a  large  part  of  the  area  occupied  by  it, 
was  deposited  in  just  such  a  manner.  The  subsoil  of  this  formation 
is  mottled  red,  yellow,  purple,  and  gray  by  the  deposition  of  hydrated 
iron  oxide  in  various  proportions  in  irregular  patterns.  A  close  ex- 
amination of  this  mottling  shows  that  the  darker  colors  outline  a  series 
of  clay  lenses,  lying  with  their  shorter  axes  nearly  vertical,  and  with 


MARYLAND   GEOLOGICAL    SURVEY  145 

their  edges  overlapping  like  the  shingles  on  a  roof.  Some  of  the  clay 
masses  are  very  regularly  lenticular,  others  are  irregular;  while  in  some 
instances  this  structure  is  only  partially  indicated.  Along  the  laps 
of  the  clay  lenses  are  to  be  found  little  seams  of  sand  with  occasionally 
pockets  or  masses  of  sand  of  greater  extent.  Some  fine  gravel  is 
mixed  with  the  sand. 

The  entire  structure  suggests  the  accumulation  of  a  large  number 
of  clay  masses  which  have  become  flattened  through  the  pressure  exerted 
by  overlying  materials.  These  clay  masses  were  probably  derived  by 
wave  action,  rolled  along  a  somewhat  sandy  shore  line  or  sea  bottom, 
and  finally  deposited  in  more  quiet  water. 

The  formation  is  almost  uniformly  underlain  by  sandy  and  gravelly 
layers  from  which  the  sand  content  might  have  been  derived;  and 
the  amount  of  sand  in  a  given  mass  decreases  as  the  line  between  the 
sand  and  clay  strata  is  farther  removed. 

This  structure  of  the  subsoil  of  the  Leonardtown  loam  is  one  of  its 
marked  characteristics,,  not  only  in  Calvert  County  but  over  larger  areas 
of  the  same  soil  formation  in  adjoining  regions.  It  indicates  a  marine 
or  estuarine  origin  and  shows  that  the  soil  was  deposited  as  a  pebble 
or  boulder  mass  of  clay  in  water  of  a  moderate  depth.  The  agricultural 
significance  of  this  peculiar  structure  is  also  marked. 

The  soil  of  the  Leonardtown  loam  areas  consists  of  a  yellow,  silty 
loam,  containing  scattered  pebbles  of  small  size.  Its  usual  depth  is 
about  one  foot  and  it  is  underlain  by  a  clay  loam  subsoil  having  the 
characteristics  already  described.  The  total  depth  of  soil  and  subsoil 
varies  greatly,  both  because  of  differences  in  thickness  of  the  original 
deposit  and  because  erosion  has  not  been  uniform  in  different  localities. 

The  Leonardtown  loam  subsoil  acts  as  a  heavy  clay  in  its  relation- 
ship to  the  circulation  and  retention  of  soil  moisture,  though  a  mechani- 
cal analysis  of  any  given  portion  of  it  would  show  it  to  be  a  somewhat 
sandy  loam. 

Water,  in  circulating  through  soils  and  subsoils,  depends  for  its  rate 
of  motion  upon  the  size  and  arrangement  of  the  spaces  existing  between 
individual  soil  particles.  Thus  a  coarse  sandy  soil  has  less  actual  open 


14:6  THE   SOILS    OF    CALVERT    COUNTY 

space  in  a  cubic  foot  of  material  than,  a  fine-grained  compact  clay  has. 
But  the  soil  pores  are  large  and  more  continuous  and  the  volume  of 
space,  compared  with  the  area  of  the  walls  of  the  cavities,  is  much 
greater  than  in  the  clay  soil.  As  a  result  water  moves  more  freely 
through  sandy  soils  than  through  clays.  Sandy  soils  are  incapable 
of  retaining  the  high  percentage  of  soil  moisture  usually  found  in  clays, 
when  all  other  conditions  but  those  of  texture  are  similar. 

With  the  Leonardtown  loam  the  actual  texture  of  the  soil  masses 
is  largely  modified  in  its  influence  upon  the  circulation  and  retention 
of  soil  moisture  by  the  peculiar  structure.  Water  in  passing  through 
the  subsoil  must  pursue  a  very  roundabout  course,  for  the  clay  lenses 
are  highly  impervious  while  the  sandy  joints  permit  of  a  much  easier 
flow.  Thus  the  soil  water  flows  from  the  surface  of  one  clay  lense  to 
that  of  another  and  is  much  more  retarded  in  its  progress  than  would 
be  the  case  if  the  same  materials  were  mixed  together  in  a  homogeneous 
mass.  As  a  consequence  the  Leonardtown  loam  presents  the  agricul- 
tural features  of  a  heavy  clay  soil  while  composed  of  the  materials 
of  a  somewhat  sandy  loam.  The  peculiar  structure  also  makes  the 
subsoil  more  friable,  and  the  Leonardtown  loam  is  frequently  spoken 
of  as  a  brittle  soil  to  distinguish  it  from  more  plastic  masses  of  clay. 

The  natural  growth  common  to  the  Leonardtown  loam  comprises  the 
white  oak,  pitch  pine,  and,  in  low-lying  wet  areas,  the  sweet  gum.  The 
white  oak  growths  are  such  a  common  feature  of  this  soil  that  it  is 
locally  known  as  white  oak  soil,  while  the  fact  that  much  of  its  area 
is  covered  with  timber  also  causes  it  to  be  spoken  of  as  forest  land. 

The  Leonardtown  loam  is  one  of  the  heaviest  soil  types  found  in 
Calvert  County,  and  with  proper  cultivation  it  should  produce  good 
crops  of  wheat  and  furnish  fair  pasturage  and  clover  crops.  It  is  too 
heavy  for  the  production  of  the  best  grades  of  tobacco,  and  consequently 
it  has  not  been  utilized  to  the  best  advantage  in  the  Maryland  areas 
where  it  occurs. 

The  uniformly  yellow  appearance  of  the  surface  soil  indicates  a  lack 
of  organic  matter,  which  should  be  supplied  in  the  form  of  stable 
manures,  and  by  plowing  under  green  crops  like  crimson  clover  and 


MARYLAND    GEOLOGICAL    SURVEY 


147 


cowpeas.  Such  a  treatment  would  not  only  increase  the  actual  supply 
of  plant  food  but  would  also  improve  the  texture  of  the  soil.  Unless 
it  is  absolutely  necessary  that  tobacco  should  be  raised  upon  areas  of 
this  type,  the  application  of  lime  should  be  tried  in  connection  with 
stable  manures  and  green  fertilizers.  The  fact  that  tobacco  is  not  largely 
raised  on  this  soil  should  make  this  line  of  improvement  much  easier 
than  on  other  types  of  soil  to  which  tobacco  is  one  of  the  crops  best 
adapted. 

The  present  production  of  wheat  and  corn  on  the  Leonardtown  loam 
is  scarcely  equal  to  the  average  of  the  county,  and  large  areas  of  the 
formation  are  left  to  forest  occupation,  furnishing  only  scanty  pas- 
turage for  a  few  head  of  stock.  The  soil  is  capable  of  considerable 
improvement  and  should  be  cleared  and  farmed  according  to  modern 
methods,  especially  in  the  production  of  grain  and  forage  crops. 

MECHANICAL  ANALYSES  OF  LEONARDTOWN  LOAM. 


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3 

P.ct. 

P.ct. 

P.ct. 

P.ct. 

P.ct. 

P.ct. 

P.ct. 

P.ct. 

5161 

Frazier  

Yellow  silty  loam, 
0  to  8  inches. 

2.94 

IT. 

2.01 

3.68 

9.38 

10.53 

59.00 

11.81 

5163 

1^4  miles  NE.  of 

Yellow  silty  loam, 

2.53 

Tr. 

2.91 

3.76 

11.83 

20.86 

50.57 

7.52 

5165 

Barstow. 
l3^    miles    W.   of 

0  to  10  inches. 

.    ..(JO  

2.58 

1.12 

4.30 

5.84 

10.42 

17.04 

46.53 

11.98 

5163 

Dares  Wharf. 
Subsoil  of  5161  

Clay  loam,  8  to  30 

2.61 

.64 

4.01 

4.54 

6.26 

13.44 

53.73 

10.81 

inches. 

5164 

Subsoil  of  5163  

Clay  loam,  10  to  30 

2.31 

.93 

2.20 

3.51 

11.22 

11.43 

47.14 

21.09 

5166 

Subsoil  of  5165  

inches. 
Clay  loam,  10  to  40 

2.12 

.80 

3.48 

5.17 

7.65 

10.44 

48.55 

21.75 

inches. 

The  Susquehanna  Gravel. 

About  six  square  miles  of  territory  in  Calvert  County  are  occupied 
by  distinctly  gravelly  soil.  The  gravels  usually  appear  on  slopes  in 
narrow  bands  and  in  isolated  patches,  but  near  Adelina  and  about  one 
mile  east  of  Ferry  Landing  considerable  areas  of  upland  are  occupied 


148  THE   SOILS    OF    CALVERT    COUNTY 

by  medium-sized  quartz  pebbles,  very  closely  coherent  and  mixed  with 
little  other  soil  material.  Also  along  some  of  the  slopes  from  the 
upland  region  to  the  lower  levels  soil  creep  and  rain  wash  have  spread 
considerable  gravel  over  the  slopes.  This  occurrence  of  gravel  is 
in  part  due  to  the  exposure  of  gravel  bands  originally  deposited  along 
with  other  material  and  in  part  to  the  concentration  of  the  gravel  by 
the  washing  away  of  finer  materials.  The  resulting  soil  conditions  are 
not  very  favorable  to  agricultural  operations. 

The  soil,  such  as  it  is,  consists  of  from  about  60  to  85  per  cent  or  even 
more  of  rounded  quartz  pebbles,  varying  in  size  from  that  of  a  pea 
to  several  inches  in  diameter.  Some  finer  material  present  gives  a 
foothood  for  vegetation,  and  near  Adelina  corn  and  tobacco  are  raised 
on  this  soil.  Where  a  heavier  subsoil  is  present,  at  no  great  depth, 
a  sufficient  water  content  can  be  maintained  to  produce  a  crop  under 
favorable  circumstances  of  rainfall. 

.In  some  localities  grapes  are  raised  on  soils  nearly  as  gravelly,  but 
it  is  done  in  a  climate  where  the  rainfall  is  greater  and  the  seasons  of 
drought  not  so  frequent  nor  so  prolonged. 

Irrigation  would  aid  in  crop  production  on  this  gravel  soil,  but  it 
is  not  well  situated  nor  of  sufficient  value  to  warrant  so  expensive  a 
remedy. 

The  Windsor  Sand. 

This  soil  formation  lies  along  the  lower  portions  of  the 
stream  divides  in  the  southern  part  of  the  county,  and  occupies  the 
highest  crests  in  the  northern  part.  The  surface  of  the  formation  is 
usually  gently  rolling  and  the  more  level  portions  of  the  type  are  in- 
terrupted by  numerous  small,  flat-topped  hills  covered  by  Norfolk  or 
Leonardtown  loam,  or  else  consisting  entirely  of  the  barren  subsoils 
of  these  formations  which  have  been  exposed  by  rain-washing.  In  some 
parts  of  the  area — notably  between  Battle  Creek  and  the  Patuxent — 
gravel  knolls  and  slopes  are  found  scattered  through  this  soil  formation. 

The  Windsor  sand  type  owes  its  origin  to  the  exposure  of  the  horizon 
of  orange-colored  sands  and  gravels  described  in  the  preceding  section 


MARYLAND   GEOLOGICAL   SURVEY  149 

on  the  geology  of  the  county.  This  layer  of  material  at  one  time 
formed  an  almost  continuous  sheet  over  all  the  upland  part  of  the 
county,  and  when  first  built  into  the  land  area  of  the  region  it  was 
covered  by  other  sediments  which  have  since  been  removed  by  erosion. 
The  remaining  portions  of  these  other  sediments  constitute  the  Norfolk 
and  Leonardtown  loam  areas  which  still  exist,  surrounded  by  bands 
or  areas  of  the  Windsor  sand  at  the  present  time.  In  many  instances 
it  is  still  possible  to  trace  the  sands  and  gravels  of  this  soil  type  to 
the  edge  of  Norfolk  or  Leonardtown  loam  areas  and  then  to  observe 
their  continuation  under  the  heavier  materials  of  those  types.  This 
fact  is  conclusive  evidence  in  itself  of  the  origin  of  the  type,  but  the 
location  of  the  type  between  stream  heads  and  along  divides,  where 
erosion  has  been  most  active,  and  its  general  presence  immediately 
over  Miocene  strata  throughout  the  entire  area  corroborate  the  more 
direct  evidence.  The  close  similarity  of  the  materials  of  the  soil  to 
those  of  the  orange-sand  and  gravel — in  many  cases  amounting  to 
complete  identity — also  supports  this  explanation  of  the  origin  of  the 
type;  that  is,  a  definite  layer  of  sedimentary  materials  has  been  exposed 
by  erosion  to  form  a  definite  soil  type.  This  is  not  the  only  case  to 
be  found  in  the  county,  as  is  indicated  under  the  discussion  of  the 
Norfolk  sand  and  the  Sassafras  loam. 

One  marked  feature  of  the  Windsor  sand  area  is  the  absence  of 
surface  streams.  The  incoherence  and  porosity  of  the  soil  allow  the 
water  falling  on  its  surface  to  sink  immediately  to  considerable  depths, 
and  the  flow  of  water  takes  place  as  a  gradual  seepage  along  the  surface 
of  slightly  more  dense  materials  lying  under  the  sand  and  gravel  of  this 
soil. 

As  a  result  stream  channels  are  only  sparingly  present  in  the  area, 
for  absence  of  surface  flow  prevents  the  formation  of  stream  ways  and 
the  small  washes  formed  by  the  most  torrential  storms  are  rapidly 
obliterated  by  the  crumbling  of  incoherent  margins  or  by  the  ordinary 
operations  of  cutivation. 

The  soil  proper  of  the  Windsor  sand  areas  consists  of  a  medium 
to  a  coarse-grained  sand,  usually  containing  considerable  quantities  of 


150  THE   SOILS    OF    CALVERT    COUNTY 

small  pebbles.  Locally  the  material  frequently  becomes  finer-grained, 
forming  a  sandy  loam  type,  but  this  is  more  usual  near  the  boundary 
with  some  other  type  where  rain- wash  havS  brought  in  finer  local  ma- 
terial. The  subsoil  is  a  rather  coarse-grained,  yellow  sand  mixed  with 
pebbles  and  broken  iron  crust  and  usually  very  loosely  coherent.  The 
soil  varies  in  depth  from  eight  inches  to  about  one  foot,  while  the  sub- 
soil may  be  three  feet  or  ten  feet  in  thickness,  depending  upon  the 
amount  of  the  material  originally  deposited  and  upon  the  progress  of 
what  little  erosion  takes  place  over  the  area.  It  is  very  uniformly  under- 
lain by  the  finer-grained  sands  and  sandy  loams  of  the  Choptank  or 
St.  Mary's  divisions  of  the  Chesapeake.  The  contact  between  the 
Windsor  sand  and  the  underlying  material  is  frequently  well  shown 
in  the  deeper  road  cuts. 

The  natural  growth  of  this  type  of  soil  in  Calvert  and  nearby  counties 
consists  of  forests  of  pitch  pine  and  yellow  pine,  which  give  it  a  dis- 
tinctive character  so  pronounced  that  where  the  forest  still  remains 
it  is  usually  easy  to  recognize  the  boundaries  and  extent  of  the  areas 
by  the  tree  growth.  It  is  also  noticeable  that  the  most  sandy  roads  of 
the  county  are,  with  few  exceptions,  found  in  areas  of  Windsor  sand. 

In  Calvert  County  this  soil  type  supports  some  of  the  finest  peach 
orchards  of  the  region.  The  fruit  is  noteworthy  for  its  fine  color  and 
flavor,  and  peach  orchards  in  the  county  remain  in  bearing  over  periods 
of  twenty-five  or  thirty  years.  Tobacco  produces  a  good  texture  of 
leaf  upon  this  soil  type,  though  the  amount  raised  per  acre  is  some- 
what less  than  on  heavier  soils.  In  especially  dry  seasons  the  plants 
are  more  liable  to  "  fire  "  on  the  Windsor  sand  than  on  soils  more  retentive 
of  moisture.  The  Windsor  sand  is  well  adapted  to  the  pro- 
duction of  early  truck  crops.  Increased  rapid  transportation  facilities 
should  permit  of  the  more  general  introduction  of  such  crops  on  this 
and  other  light  soil  types  in  the  county. 

The  inability  of  so  light  and  porous  a  type  of  soil  to  maintain  a 
sufficient  amount  of  soil  moisture  for  plant  growth  during  periods  of 
drought  may  be  corrected  in  part  by  the  more  general  use  of  green 
manures  plowed  under,  crimson  clover  and  cowpeas  being  well  adapted 
to  such  uses. 


MARYLAND   GEOLOGICAL    SURVEY 


151 


The  coarseness  of  the  grains  forming  this  soil  is  indicated  by  the 
analyses  of  typical  soil  and  subsoil : 

MECHANICAL  ANALYSES  OF  WINDSOR  SAND. 


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33    15 

5167 

1  mile  E.  of  Prince 
Frederick. 

Coarse  sand  and 
gravel,  0  to  12 

P.ct 
0.97 

P.ct. 
10.31 

P.ct. 
34.75 

P.ct. 
23.06 

P.ct. 
13.95 

P.ct. 

4.52 

-P.ct.  P.ct. 
9.85    2.65 

inches 

5168 

Subsoil  of  5167  

Coarse  sand  and 
gravel,  12  to  40 

1.02 

8.88 

30.92 

20.62 

13.68 

6.10 

15.28 

4.66 

inches. 

Sand. 

The  Norfolk  sand  is  found  along  the  sides  of  all  the  deeper  stream 
cuts  in  the  southern  portion  of  the  county,  and  it  occupies  about 
50  per  cent  of  the  land  surface  in  the  northern  half  of  the  county, 
covering  slopes  and  upland  alike  except  where  other  upland  soil  types 
still  exist  in  fragmentary  areas. 

The  surface  of  this  formation,  where  it  occurs  along  stream  valleys,  is 
generally  quite  steeply  inclined  and  often  precipitous.  As  a  result 
most  of  the  areas  of  this  type  in  southern  Calvert  County  are  occupied 
by  growths  of  pine,  being  too  steep  to  permit  agricultural  operations. 
In  the  northern  part  of  the  county  and  along  certain  stream  terraces, 
like  those  in  the  Hunting  Creek  valley,  the  Norfolk  sand  forms  one 
of  the  most  important  soil  types. 

The  Norfolk  sand,  as  a  soil  type,  owes  its  origin  to  three  different 
methods  of  derivation.  The  greater  number  of  the  areas  of  this  soil, 
found  in  Calvert  County,  are  derived  from  the  outcrops  of  layers  of 
sandy  material  deposited  under  water  during  Miocene  and  Pleistocene 
time.  Two  of  the  sub-divisions  of  the  Miocene  are  made  up 
largely  of  medium-grained  sands,  interspersed  with  thin  strata  of  clay 
and  layers  of  shell  marl.  One  member  of  the  Pleistocene,  found  lying 


152  THE   SOILS    OF    CALVERT    COUNTY 

above  the  Miocene  in  many  places,  consists  of  a  medium-grained  sand 
containing  small  pebbles  and  considerable  iron  crust.  Where  these 
different  layers  of  sandy  material  have  been  exposed  at  the  surface 
through  stream  erosion,  the  various  agencies  of  weathering,  such  as 
frost,  percolating  rain,  and  organic  growth,  have  modified  the 
originally  infertile  sands,  so  that  they  are  capable  of  sustaining  vege- 
tation and  have  become  true  soils.  So  areas  of  the  resulting  Norfolk 
sand  are  found  in  the  stream  beds,  where  these  layers  outcrop,  and  over 
the  upland  portion  of  the  county  where  overlying  materials  have  been 
removed. 

This  process  of  soil  formation  has  occupied  a  long  period  of  time; 
and  while  part  of  the  sandy  material  was  being  worked  over  into  soil 
where  it  lay,  part  of  it  was  carried  away  by  the  streams  and  dropped 
along  the  stream  courses  and  at  tide  water  wherever  the  current  was 
not  swift  enough  to  continue  carrying  its  load  of  sand.  The  present 
shore  line  lies  considerably  below  the  level  of  the  position  it  occupied 
when  this  action  began,  so  that  the  first  deposits  of  this  transported 
sand  were  in  the  form  of  terraces  built  far  above  the  present  mouths 
of  the  streams.  With  the  relative  lowering  of  the  water  level  these 
terraces  have  been  exposed  to  the  agencies  of  the  atmosphere  and  these 
sands  have  come  to  form  soils  very  similar  to  the  ones  directly  derived 
from  the  outcrops  of  the  original  material.  Such  terraces  may  be 
seen  near  Hunting  Creek  bridge,  along  Lyons  Creek,  and  in  many 
other  localities.  Part  of  the  sand  was  also  carried  down  as  far  as 
the  areas  at  present  occupied  by  the  foreland  portion  of  the  county 
along  the  Patuxent  Eiver,  and  areas  of  Norfolk  sand  are  found  about 
one  mile  south  of  Deep  Landing  just  north  of  Ferry  Landing.  They 
represent  a  terrace  built  by  the  Patuxent,  in  most  respects  similar  to 
those  built  by  the  smaller  streams. 

A  common  peculiarity  of  all  these  terraces  is  that  the  sand  is  coarser 
and  the  gravel  more  aboundant  as  one  goes  up  stream.  This  is  due 
to  the  diminished  strength  of  stream  currents  near  their  mouths  and 
the  consequent  diminution  of  the  size  of  the  particles  transported. 

In  the  northwestern  part  of  the  county  and,  in  general,  north  of  the 


MARYLAND   GEOLOGICAL    SURVEY  153 

latitude  of  Huntingtown  the  sands  of  the  Norfolk  sand  are  not  so 
coarse  as  farther  to  the  south,  and  a  sticky  clayey  subsoil  is  reached  at 
a  less  depth.  This  is  due  to  the  fact  that  the  lowest  divisions  of  the 
Miocene — the  Calvert  clay  and  diatomaceous  earth — comes  out  at  the 
surface  and  the  sandy  materials  which  once  covered  it  have  been  more 
completely  removed.  However,  the  sandy  layers  are  still  represented 
by  small  areas  on  the  higher  uplands,  and  the  long-continued  and  con- 
stant rain  wash  has  spread  a  thin  layer  of  sand  even  over  the  heavier 
subsoils.  This  action  is  still  in  progress  and  many  acres  of  this  soil 
type  consist  of  rain  washed  materials  which  have  accumulated  in  hollows 
and  valleys. 

The  agricultural  values  of  these  ddfferent  accumulations  remain 
remarkably  constant,  so  they  have  been  classed  as  a  single  soil  type 
though  varying  considerably  in  origin  and  in  geologic  age. 

The  Norfolk  sand  is  a  yellowish  sandy  loam  of  medium  coarseness, 
containing  a  scattering  of  gravel  in  some  instances  and  very  often 
mingled  with  broken  fragments  of  iron  crust.  The  soil  has  an  average 
depth  of  about  nine  inches  and  is  usually  succeeded  by  a  slightly  heavier 
yellow,  sandy  loam,  which  may  extend  to  a  depth  of  many  feet,  as 
in  the  case  of  the  areas  weathered  out  from  outcropping  strata  or  which 
may  be  underlain  at  various  depths  by  much  finer-grained  material,  as 
is  frequently  the  case  in  northern  Calvert  County. 

The  natural  timber  growth  is  pitch  pine,  chestnut,  and  oak.  The 
soil  is  one  largely  used  for  the  cultivation  of  tobacco  at  present,  and 
some  of  the  best  tobacco  farms  in  the  area  are  located  on  this  type. 
On  the  other  hand  a  few  farms,  located  near  the  Patuxent  Kiver,  on 
this  type,  are  reported  as  not  so  successful  in  the  production  of  the  crop 
for,  while  a  large  growth  is  secured,  the  quality  is  not  of  the  best. 

The  Norfolk  sand,  as  represented  by  the  finer-grained  grades  of 
northern  and  northwestern  Calvert  County,  produces  good  crops  of 
tobacco,  and  the  type  in  general  is  also  well  adapted  to  the  production 
of  truck  crops.  The  peaches  raised  upon  this  soil  are  of  good  color 
and  bring  good  returns.  Wheat  and  corn  are  raised  in  regular  rotation 
with  tobacco,  but  the  Norfolk  sand  is  a  type  distinctly  too  sandy 
11 


154 


THE   SOILS    OF    CALVERT    COUNTY 


for  the  production  of  the  best  grain  crops.  It  is  not  sufficiently 
retentive  of  water  to  maintain  the  continuous  growth  necessary  to 
bring  grains,  especially  wheat,  to  maturity. 

The  increased  facilities  for  rapid  transportation,  recently  acquired 
in  northern  Calvert  County,  should  lead  to  a  more  general  use  of  this 
soil  for  market  gardening  purposes.  It  is  one  of  the  typical  truck  soils 
of  the  Atlantic  seaboard. 

The  slight  gradation  in  the  texture  of  this  soil  type  is  well  shown  by 
the  following  analyses.  The  finest-grained  soils  are  found  toward  the 
northern  extremity  of  Calvert  County,  while  the  coarsest  sands  are  found 
near  its  southern  end.  The  intermediate  texture  of  the  Hunting  Creek 
sample  is  quite  marked. 

MECHANICAL  ANALYSES  OF  NORFOLK  SAND. 


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One-   our  th    mile 
N.  of  St.  Leonard. 

Medium   brown 
sandy  loam,0  to 

P.ct. 
1.42 

P.ct. 
1.06 

P.ct. 

6.08 

P.ct. 
10.06 

-P.ct. 
51.44 

P.ct. 
10.84 

P.ct. 
16.40 

P.ct. 
3.65 

10  inches. 

5171 

1  mile  E.  of  Hunt- 
ing Creek  Bridge. 

Orange  sandy 
loam  ,    0   to   9 

1.33 

.68 

2.49 

6.28 

48.36 

20.99 

16.33 

3.51 

inches. 

5176 

One-half   mile  N. 
of    Mount    Har- 

Yellow  sandy 
loam,   0   to   9 

1.70 

Tr. 

1.33 

2.36 

47.38 

26.20 

16.95 

3.68 

5170 

mony. 
Subsoil  of  5169  

inches. 
Orange  sand  y 

2.11 

.70 

4.00 

7.08* 

51.98 

7.27 

16.51 

10.66 

loam,  9  to  30 

inches. 

5172 

Subsoil  of  5171 

do 

1-11 

Tr 

3.06 

6.09 

49.73 

17  16 

16  14 

A   O« 

5177 

Subsoil  of  6176.... 

Yellow  sandy 
loam,  9  to  30 

1.48 

-Lr. 
0.00 

Tr. 

2.40 

43.33 

26.59 

19.65 

6.59 

inches. 

The  Sassafras  Loam. 

ISTo  large  single  areas  of  Sassafras  loam  are  found,  but  small  tracts 
occur  throughout  the  county.  They  are  found  more  often  and  in  larger 
areas  in  the  northern  part  of  the  county  than  in  the  southern. 

The  Sassafras  loam  in  Calvert  County  is  derived  from  two  separate 


MARYLAND   GEOLOGICAL    SURVEY  155 

sources.  The  lowest  member  of  the  Chesapeake  Group,  the  Calvert, 
is  made  up  of  beds  of  diatomaceous  earth  and  clay,  and  where  these 
reach  the  surface  the  resulting  soil  is  a  slightly  sandy  loam  derived 
directly  through  the  action  of  atmospheric  agencies  upon  the  clay  and 
diatomaceous  earth.  The  areas  of  soil  thus  formed  are  found  along 
the  slopes  of  stream  valleys  and  are  usually  merely  long  narrow 
strips  of  a  heavier  soil  separating  the  higher,  sandy  soils  from  low, 
sandy  terraces,  or  from  meadow  lands  in  the  stream  bottom.  Frequently 
the  horizon  which  would  be  occupied  by  this  soil  type  forms  a  steep 
cliff  of  clayey  material  unadapted  for  agricultural  purposes.  This  zone 
of  Sassafras  loam  does  not  always  show  the  soil  formation  in  its  most 
typical  character,  since  it  lies  in  a  position  to  catch  much  of  the  sandier 
material  washed  down  by  rains  from  higher  levels.  In  these  cases 
the  soil  is  more  sandy  than  in  type  localities,  but  the  subsoil  is  the 
usual  heavy  clay  found  elsewhere  throughout  this  formation. 

Lying  along  the  stream  valleys  and  along  the  Patuxent  slope  are 
flat-topped  terraces  built  up  in  recent  geological  times  from  materials 
which  have  been  derived  from  the  Calvert  clays  and  reworked  into 
later  deposits.  So  far  as  soil  values  are  concerned,  these  materials 
form  the  same  soil  types  as  when  they  composed  part  of  the  Miocene 
strata,  though  they  now  occur  as  terrace  forms.  A  terrace  of  this 
character  is  well  developed  at  about  80  feet  elevation  just  west  of 
the  head  of  tide  water  on  St.  Leonard  Creek,  another  is  found  just 
southwest  of  Dares  Wharf,  and  many  more  examples  could  be  cited 
from  localities  along  the  Patuxent.  The  region  lying  just  east  of  Lower 
Marlboro  presents  an  area  where  the  Sassafras  loam  terrace  of  later 
age  rests  against  the  outcrop  of  Miocene  material,  giving  rise  to  the 
same  soil  type  and  the  resulting  occurrence  of  Sassafras  loam  is  one 
of  the  largest  to  be  found  in  Calvert  County. 

The  influence  of  this  heavy  clayey  material  as  it  occurs  at  Miocene 
horizons  is  felt  in  the  northern  areas  of  Norfolk  sand.  The  clay  comes 
near  the  surface,  under  the  covering  of  sandy  soil,  and  in  some  cases 
forms  sticky  bands  of  small  extent  in  fields  otherwise  uniformly  cov- 
ered by  the  sands  of  the  Norfolk  sand. 


156 


THE   SOILS    OF    CALVEET    COUNTY 


The  topography  of  the  surface  of  this  soil  varies  with  its  manner 
of  occurrence.  In  the  terrace  areas  it  is  flat-topped  or  gently  sloping, 
while  in  the  outcrop  areas  it  is  more  steeply  sloping  or  even  precipitous 
and  considerably  gullied  by  stream  action. 

The  soil  itself  consists  of  a  silty  to  fine  sandy,  yellow  or  brown 
loam,  having  a  depth  of  about  ten  inches.  This  soil  is  uniformly  under- 
lain by  a  yellow  loam  of  a  finer  texture  than  the  soil,  usually  to  a 
depth  of  forty  or  fifty  inches.  In  the  outcrop  areas  of  this  type  the 
subsoil  grades  down  into  the  unweathered  bluish  clay  of  the  Calvert 
formation;  while  in  the  terrace  areas,  as  at  Dares  Wharf,  the  subsoil 
is  underlain  by  cross-bedded  sands. 

The  Sassafras  loam  is  a  type  of  soil  well  adapted  to  general  farming 
purposes,  and  if  it  occurred  in  larger  areas  would  form  a  marked  class 
of  farming  lands.  It  produces  some  of  the  best  corn  crops  raised  in 
the  county  and  produces  fair  wheat  yields.  It  is  also  cultivated  in 
tobacco  with  good  results.  In  other  regions  than  Calvert  County  this 
soil  supports  excellent  pear  orchards  and  furnishes  good  crops  of  tomatoes 
and  asparagus. 

The  following  analyses  give  an  indication  of  the  texture  of  the  Sassa- 
fras loam.  The  percentage  of  clay  in  this  soil  is  less  than  that  in  either 
the  Norfolk  or  Leonardtown  loam. 

MECHANICAL  ANALYSES  OF  SASSAFRAS  LOAM. 


1 

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3 

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a 

2 

2 

2 

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No. 

Locality. 

Description. 

«  K 

So 

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.08 

SB 

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0 

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a 

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6 

s 

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5 

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P.ct. 

P.ct. 

P.ct. 

P.ct. 

P.ct. 

P.ct. 

P.ct. 

P.ct. 

5180 

1  mile   W.  of   St. 

Yellow  silty  loam 

2.67 

0.84 

4.07 

4.38 

6.48 

12.72 

60.72 

7.80 

Leonard. 

0  to  20  inches. 

5182 

One-fourth  mile  S. 
of  Dares  Wharf. 

Yellow  loam,  0  to 
9  inches. 

2.35 

.46 

3.01 

6.55 

25.10 

15.29 

33.15 

10.74 

5181 

Subsoil  of  5180  Yellow  loam,  20  to 

2.07 

.49 

3.94 

3.78 

4.36 

8.17 

54.67 

22.39 

36  inches. 

6183 

Subsoil  of  5182.  .. 

Yellow  loam.  9  to 

2-37 

.31 

2.08 

4.67 

21.58 

15.37 

32.86 

20.53 

30  inches. 

MARYLAND   GEOLOGICAL    SURVEY  157 

The  Sassafras  Sandy  Loam. 

The  Sassafras  sandy  loam  lies  chiefly  along  the  low  forelands  which 
border  the  Patuxent  Eiver,  and  is  also  represented  by  small  areas  near 
Plum  Point  and  along  the  lower  course  of  Fishing  Creek. 

The  surface  of  this  formation  is  usually  flat  and  only  gently  sloping. 
It  lies  at  an  elevation  of  from  15  to  35  feet  above  tide  level  and  its  loca- 
tion near  tide  water,  together  with  its  altitude  and  its  crop  values,  makes 
it  one  of  the  most  desirable  soil  types  in  the  region.  It  forms  a  por- 
tion of  the  area  included  in  the  most  recent  geologic  formations  of  the 
region  and  represents  a  deposition  of  fine  sand,  silt,  and  organic  matter 
in  the  shallower  waters  of  the  latest  stage  of  land  submersion.  A  very 
similar  process  is  being  carried  on  at  present  along  the  coast,  where 
lagoons  and  stream  mouths  are  being  silted  up  after  each  rain  storm. 
The  present  marsh  areas  along  the  Patuxent  with  their  abundant  growth 
of  aqueous  vegetation  serve  as  a  filter  which  entangles  the  sediment 
carried  by  the  river  and  retains  it,  mingled  with  decaying  vegetation, 
to  form  a  soil  much  like  the  Sassafras  sandy  loam  when  a  change  in 
comparative  land  elevations  shall  expose  these  areas  as  portions  of  the 
land.  So  in  former  times  along  the  river  shores,  in  the  embayments 
formed  by  tributary  streams,  and  where  sand  bars  sheltered  areas  of 
shallow  water,  the  materials  of  the  Sassafras  sandy  loam  were  accu- 
mulated and  they  now  form  a  portion  of  the  land  well  known  for  its 
fertility.  Small  areas  of  especially  sandy  soil  lying  within  the  boun- 
daries of  this  type — notably  near  Point  Patience — are  still  in  the  pro- 
cess of  formation.  The  wind  sweeping  along  a  sandy  shore  line  and 
against  a  low  cliff  picks  up  sand  from  the  beach  and,  when  the  direction 
of  its  current  is  changed  by  the  cliff,  eddies  are  set  up  which  allow  part 
of  the  sand  to  drop  on  the  nearby  fields.  Small  patches  of  a  few  acres 
in  extent  are  made  excessively  sandy  and  their  adaptation  to  crops  is 
materially  changed  by  this  process. 

The  Sassafras  sandy  loam  may  be  defined  as  consisting  of  a  medium 
to  fine,  brown,  sandy  loam,  having  an  average  depth  of  a  foot  or  more.  It 
is  underlain  by  a  heavier  type  of  yellow  sandy  loam  to  an  average  depth 
of  about  four  feet  and  this  is  often,  though  not  always,  succeeded  by  a 


158 


THE    SOILS    OF    CALVERT    COUNTY 


gray  or  drab  clay  loam.  This  combination  of  soil  textures  gives  rise  to 
an  easily  worked  soil  sufficiently  retentive  of  moisture  to  favor  the  pro- 
duction of  grain  crops,  but  not  so  heavy  and  wet  as  to  exclude  the  culti- 
vation of  late  truck  crops  and  fruit.  Tobacco  is  also  raised,  though  it 
is  not  so  well  suited  to  tobacco  culture  as  are  other  sandier  soil  types 
located  in  the  county. 

Stock-raising  and  dairying  are  carried  on  upon  this  soil  type  in  a  few 
localities  in  the  southern  part  of  Calvert  County,  while  the  cultivation 
of  crops  for  canning  factories  is  undertaken  upon  this  type  of  soil  in 
other  localities. 

The  natural  forest  growth  has  been  removed  from  the  Sassafras  sandy 
loam  and  at  present  almost  the  entire  extent  of  the  formation  is  under 
cultivation. 

The  following  analyses  of  a  typical  sample  of  the  soil  and  subsoil 
of  this  type  show  the  sandy  character  of  this  loam : 

MECHANICAL  ANALYSES  OF  SASSAFRAS  SANDY  LOAM. 


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us 

0 

i 

2 

3 

g 

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Locality. 

Description. 

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So 

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3 

c"a 
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i 

um  sai 
0.25m 

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0.05m 

0.05  to  C 

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2 

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fl 

3 

S 

I 

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3 

0 

S 

S 

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33 

| 

P.ct. 

P.ct. 

P.ct. 

P.cl. 

P.ct. 

P.ct. 

P.ct. 

P.ct. 

5184 

One-half  mile  N.  of    Brown  sandy  loam. 

2.98 

0.66 

3.10 

5.52 

31.94 

20.92 

29.63 

6.30 

Point  Patience. 

0  to  14  inches. 

5185 

Subsoil  of  5184  

Yellow  fine  sandy 
loam,   14   to   30 

1.76 

.48 

3.08 

5.30 

26.16 

20.24 

33.29 

9.54 

inches. 

The  Meadow  Land. 

The  local  significance  of  the  word  meadow  varies  so  greatly  in  different 
localities  that  it  may  be  well  to  define  its  use  in  this  report  as  referring 
only  to  low-lying,  generally  rather  wet  areas,  having  an  approximately 
flat  surface  and  best  adapted  to  the  production  of  grasses  and  to  grazing. 

In  Calvert  County  meadow  areas  are  found  exclusively  along  the 
bottoms  of  the  larger  stream  valleys  and  on  the  lower-lying  portions  of 


MARYLAND    GEOLOGICAL    SURVEY  159 

the  forelands  bordering  the  Patuxent  Eiver.  The  chief  difference  be- 
tween these  areas  is  found  in  their  extent.  The  stream  valleys  are  nar- 
row and  steep-walled,  and  the  level  or  gently  sloping  portions  of  their 
bottoms  are  the  only  parts  of  the  upland  forming  typical  meadows. 
Even  portions  of  these  stream  bottoms  are  so  wet  and  ill-drained  as  to 
fall  in  the  general  classification  of  swamps,  as  is  the  case  with  the  lower 
courses  of  Pishing  Creek,  Parker  Creek,  and  other  large  streams. 

The  meadow  lands  of  the  stream  valleys  owe  their  origin  primarily 
to  the  action  of  the  streams  themselves.  Channels  have  been  and  are 
being  cut  into  the  unconsolidated  materials  which  constitute  the  region 
and  the  changing  locations  of  the  larger  streams  have  broadened  these 
valleys. 

Then,  too,  local  material  contributed  by  every  storm  is  carried  part 
way  from  the  upland  to  the  sea  and  is  left  temporarily  at  different  points 
along  the  valley.  In  some  cases  deposits  of  sand  and  gravel  are  formed; 
in  others,  clay  and  silt  are  deposited  and  a  very  irregular  soil  results. 
The  common  characteristic  of  this  entire  soil  mass  is  its  moist  condition 
resulting  entirely  from  its  position  relative  to  stream  drainage. 

Upon  these  meadow  areas  a  rank  growth  of  poplar,  sweet  gum,  alder, 
and  a  few  pines  and  oaks  is  found,  generally  overgrown  by  climbing 
vines  and  interspersed  in  the  more  open  portions  by  banks  of  ferns  and 
areas  of  coarse  rank  grasses.  The  position,  attitude,  and  moisture  con- 
ditions are  not  favorable  to  the  cultivation  of  crops  and  the  only  real 
use  made  of  these  lands  is  to  turn  farm  animals  upon  them  to  graze. 
The  open  winters  of  the  region  permit  of  almost  constant  grazing,  though 
some  of  the  meadow  areas  are  frequently  flooded  to  such  an  extent  that 
they  become  inaccessible. 

The  meadow  lands  lying  along  the  forelands  are  somewhat  different. 
They  comprise  low-lying  areas  which,  on  account  of  the  fine  texture  of 
the  soil  or  because  of  their  position  near  water  level,  are  not  so  valuable 
for  general  agricultural  purposes  as  the  prevailing  soil  types.  How- 
ever, these  meadow  lands  are  frequently  cleared  and  fair  crops,  especially 
grain  crops,  can  be  raised  on  them. 

The  foreland  meadows  owe  their  origin  to  the  deposition  of  fine  silt 


160  THE    SOILS    OF    CALVERT    COUNTY 

and  clay  when  the  area  was  submerged  and  to  the  partial  establishment 
of  natural  drainage  since  they  became  a  part  of  the  land  area.  They 
are  flat  or  gently  rolling  and  there  is  no  marked  rise  in  elevation  in 
passing  from  the  meadow  land  to  the  Sassafras  sandy  loam.  There  is, 
however,  a  marked  change  in  soil  texture  in  most  cases. 

The  foreland  meadows  generally  have  a  depth  of  about  one  foot  of 
gray  or  drab-colored  silty  or  clayey  loam,  underlain  by  three  or  four 
feet  of  drab  clay.  This  is  frequently  succeeded  by  gravel  and  sand 
extending  downward  to  sea  level.  The  clay,  though  tough  and  plastic 
when  wet,  will  leach  out  and  fall  apart  if  long  exposed  to  the  action  of 
the  rain  and  frost.  This  same  soil  type,  if  lying  farther  above  perma- 
nent water  level,  would  correspond  closely  in  texture  and  crop  values  to 
the  Sassafras  loam. 

At  present  these  meadow  lands  are  largely  covered  with  growths  of 
sweet  gum,  water  oak,  and  other  water-loving  trees.  Where  cultivated 
they  produce  a  fair  crop  of  wheat  or  grass,  but  are  not  very  well  adapted 
to  the  culture  of  fruit,  truck,  or  tobacco.  One  peach  orchard  seen  on 
this  soil  type  looked  sickly  and  the  fruit  was  not  well  colored. 

Artificial  underdrainage  and  a  resort  to  liming  would  improve  this 
land  and  help  to  bring  it  into  a  fair  state  of  productiveness.  Wheat  and 
grass  should  be  its  chief  crops.  The  valley  meadows,  on  the  other  hand, 
are  only  adapted  to  grazing  and  the  wild  grasses  now  produced  are  not 
particularly  nourishing. 

The  Swamp  Land. 

The  mouths  of  nearly  all  the  larger  streams  in  Calvert  County  are 
marked  by  areas  of  marshy  land.  This  condition  is  brought  about 
through  two  chief  causes.  In  the  first  place  sand  and  clay  derived  from 
the  upland  is  being  deposited  near  the  mouths  of  all  the  streams  and 
the  land  area  is  growing  slowly.  The  first  step  in  this  growth  is  the 
shallowing  of  water  areas  through  deposition,  then  vegetation  gains  a 
foothold  and  swamp  areas  grown  up  to  reeds,  calamus,  and  marsh  grasses 
are  formed.  But  this  building  up  is  impeded  to  a  very  slight  extent 
through  this  region  by  the  slow  sinking  of  the  land.  However,  the  silt- 


MARYLAND   GEOLOGICAL   SURVEY  161 

ing  up  of  streams  is  progressing  so  rapidly  that  areas  which  once  per- 
mitted navigation  by  small  boats  now  form  tide  flats  and  marshes.  This 
is  notably  the  case  along  the  lower  course  of  Hunting  Creek  and  at  the 
mouths  of  streams  flowing  into  the  Patuxent.  Along  the  Bay  shore  the 
waves  are  cutting  away  the  coast  line  so  rapidly  that  marshes  are  not 
formed  so  extensively.  The  mouths  of  Fishing  Creek  and  of  Parker 
Creek  are  swampy  and  the  sand  bar  built  up  by  wave  action  at  Cove 
Point  encloses  a  marshy  lagoon. 

These  swamp  areas  and  the  more  extensive  marshes  formed  by  the 
silting  up  of  the  Patuxent  Eiver  do  not  form  a  part  of  the  agricultural 
area  of  the  county.  In  some  places  diking  and  drainage  might  reclaim 
parts  of  the  swamp  areas.  The  swamps  would  be  made  to  furnish  a 
supply  of  muck  and  peat  for  composting  with  stable  manures  and  also 
lime  which  would  form  a  very  desirable  fertilizer.  In  their  present  state 
the  muck  and  peat  are  not  sufficiently  decomposed  to  furnish  an  imme- 
diate supply  of  plant  food. 

AGRICULTURAL  CONDITION. 

The  consideration  of  the  possibilities  of  development  of  any  agri- 
cultural region  must  depend  upon  the  soil,  climate,  and  transportation 
facilities,  combined  with  the  physical  and  mental  energy  of  its  inhabi- 
tants and  upon  other  social  and  industrial  conditions. 

Eight  distinct  soil  types  are  found  in  Calvert  County.  The  areas  of 
these  soil  types  and  their  boundaries  and  positions  have  been  determined 
by  this  survey.  Their  origin,  their  peculiarities,  their  present  produc- 
tion, and  something  of  their  capabilities  are  here  discussed  and 
the  accompanying  map  shows  their  distribution.  The  facts  as  determined 
may  be  summarized  briefly. 

The  Norfolk  loam  occupies  scattered  areas  of  the  upland.  The  soil 
is  a  silty  to  fine  sandy  loam  underlain  by  a  slightly  heavier  subsoil.  The 
usual  crops  of  the  region  are  raised  upon  this  soil  and  it  is  recognized 
as  desirable  land  for  the  production  of  corn,  wheat,  and  tobacco.  The 
character  of  the  soil  regarding  texture,  drainage,  and  location  leads  to 
its  classification  as  a  soil  adapted  to  the  production  of  the  late  truck 


162  THE    SOILS    OF    CALVERT    COUNTY 

crops  like  tomatoes,  cabbage,  green  peas,  and  other  crops  such  as  are 
produced  for  the  purpose  of  canning  in  other  regions.  In  addition  to 
these  special  crops  it  is  desirable  soil  for  rather  general  farming.  Other 
conditions  to  be.  discussed  later  have  prevented  much  specialization  as 
to  crops  and  the  Norfolk  loam  is  not  producing  crops  to  its  best  advantage. 

The  Leonardtown  loam  is  a  heavier  type  of  soil.  The  yellow,  silty 
soil  is  underlain  by  a  clayey  subsoil  of  peculiar  structure.  Only  small 
areas  of  this  soil  are  found  in  the  northern  part  of  the  county  but  a 
large  part  of  the  upland  to  the  south  is  covered  by  this  type.  It  is  quite 
extensively  timbered  with  oak  and  pitch  pine.  The  cultivated  areas 
produce  small  crops  of  wheat  and  corn  and  generally  an  inferior  grade 
of  tobacco.  The  soil  is  closely  comparable  in  its  texture  with 
the  well-known  fertile  clay  soils  of  the  valley  of  Virginia  and  of  the 
limestone  areas  of  Pennsylvania,  Kentucky,  and  other  regions.  These 
soils  are  noted  for  the  crops  of  wheat  and  grass  produced,  while  the 
similar  Leonardtown  loam  is  largely  abandoned  to  forest  growth.  There 
is  probably  no  single  cause  for  this  difference. 

The  causes  are  partly  due  to  economic  and  social  conditions  and  partly 
to  the  faulty  agricultural  methods.  The  limestone  soils  in  their  natural 
state  contain  little  or  no  lime  as  they  are  formed  from  the  residue  of 
the  decay  of  beds  of  limestone,  but  they  have  a  compact  heavy  texture.  The 
Leonardtown  loam  contains  little  lime  as  it  is  made  up  of  particles  of 
sand,  silt,  and  clay  long  washed  by  water  before  being  deposited  in 
their  present  position.  The  limestone  soils  are  frequently  treated  with 
top-dressings  of  lime  burned  by  the  farmers  themselves  from  the  under- 
lying rock.  Very  few,  if  any,  of  the  Leonardtown  loam  areas  have  been 
treated  with  lime  in  recent  years,  since  copious  liming  injures  the  quality 
of  the  tobacco  crop.  A  very  simple  test  shows  that  the  Leonardtown 
loam  is  decidedly  an  acid  soil  either  in  cultivated  fields  or  in  the  forest 
areas.  This  acid  tendency,  particularly  harmful  to  leguminous  crops 
like  peas  and  clover,  could  be  easily  counteracted  by  the  application  of 
lime.  Moreover,  the  pale  yellow  color  of  this  soil  denotes  a  deficiency  in 
organic  material,  which  should  be  supplied  in  the  form  of  stable  manures 
or  of  green  crops  plowed  Tinder.  Both  barnyard  manure  and  green 


MARYLAND   GEOLOGICAL   SURVEY  163 

manure  are  most  beneficial  to  this  soil  when  in  a  run-down  condition, 
but  the  effects  from  applications  of  green  manure  are  decidedly  more 
beneficial  in  that  they  are  more  lasting  than  for  equal  amounts  of  barn- 
yard manure.  The  benefits  from  liming  are  obvious,  while  potash  and 
nitrogen  in  combination  with  manure  are  sufficiently  beneficial  to  justify 
their  application,  at  least  in  amounts  not  to  exceed  250  pounds  per  acre, 
but  the  results  do  not  seem  to  indicate  that  when  applied 
alone  they  are  of  enough  effect  to  warrant  their  use.  The 
Leonardtown  loam  is  capable,  under  proper  tillage,  of  producing 
wheat  and  grass  to  much  better  advantage  than  it  does  at  present.  But 
the  tobacco  crop,  unsuited  to  so  heavy  a  soil,  must  be  omitted  from  the 
rotation;  and  lime,  stable  manure,  and  green  manures  employed.  The 
raising  of  stock,  undertaken  at  first  in  a  small  way,  would  make  possible 
this  very  necessary  change  of  conditions  while  aiding  materially  in  the 
improvement  of  the  soil. 

The  Susquehanna  gravels  consist  of  such  coarse  material  that  they  do 
not  maintain  a  sufficient  moisture  supply  for  the  maturing  of  crops 
which  require  a  long  period  of  growth.  The  gravel  areas  are  difficult  to 
improve  and  though  adapted  to  the  production  of  grapes,  as  is  shown  by 
the  experience  of  other  localities,  it  is  probable  that  an  intelligent  system 
of  forestation  would  bring  better  results  in  the  long  run  than  would 
any  other  treatment  of  such  areas. 

The  Windsor  sand  soil  type  on  account  of  its  coarse  texture  maintains 
but  a  small  supply  of  water  and  while  not  fitted  for  the  production  of 
large  grain  crops  it  is  classified  with  those  soils  upon  which  may  be 
produced  crops  of  early  truck,  whose  special  value  depends  upon  early 
maturity  and  a  strong  market.  The  type,  is  widespread  along  the  At- 
lantic seaboard  and  its  northernmost  extension  in  the  Connecticut  Val- 
ley furnishes  an  area  suited  to  the  production  of  wrapper-leaf  tobaccos. 
The  climatic  conditions  of  the  two  regions  are  somewhat  different 
Carefully  conducted  experiments  in  the  production  of  the  higher  grades 
of  wrapper  tobacco  should  be  undertaken  on  this  soil.  The  peach  crop 
raised  upon  this  soil  at  present  is  notable  for  the  beauty  and  quality  of 


164  THE    SOILS   OF    CALVERT    COUNTY 

the  fruit.     The  orchards  can  be  maintained  for  a  period  of  25  to  35 
•years  in  this  general  region. 

The  Windsor  sand  presents  a  type  of  soil  suited  to  intensive  rather 
than  to  extensive  farming  and  a  further  specialization  of  crops  is  advi- 
sable and  has  promise  of  considerable  success. 

The  Norfolk  sand  is  a  finer-grained  type  of  soil,  which  is  very  well 
adapted  to  the  production  of  the  typical  Maryland  grade  of  tobacco. 
It  is  a  reddish  sandy  soil  composed  of  medium  sand  and  a  small  amount 
of  silt  and  clay.  It  produces  a  bright  colory  leaf  well  adapted  to  the 
export  trade.  The  value  of  this  soil  for  tobacco  production  is  recog- 
nized locally  by  the  common  statement  that  "  the  red  lands  are  the  best 
for  tobacco."  The  Norfolk  sand  is  the  most  common  red  soil  of  the 
region.  In  other  localities  along  the  Atlantic  coast  it  is  utilized  as  a 
truck  soil,  and  even  when  not  so  favorably  located  with  regard  to  markets 
as  the  Calvert  County  areas  it  has  attained  a  considerable  prominence 
in  producing  such  crops.  The  soil  is  easily  worked  and  responds  readily 
to  careful  cultivation.  Increasing  transportation  facilities  will  make  it 
more  and  more  valuable  for  the  production  of  truck. 

The  Sassafras  loam  presents  the  features  of  a  slightly  sandy  loam 
soil,  underlain  by  a  heavier  loam  subsoil.  Its  texture  fits  it  for  the  pro- 
duction of  grain  crops  while  not  excluding  the  production  of  some  to- 
bacco, though  that  crop  can  be  raised  to  better  advantage  on  other  soils 
already  discussed.  The  Sassafras  loam  in  other  localities  has  proved 
to  be  an  excellent  soil  for  general  farming  purposes,  producing  18  to  25 
bushels  of  wheat  and  45  to  60  bushels  of  corn  per  acre  in  favorable  seasons. 
Experience  has  shown  that  peaches,  pears,  asparagus,  tomatoes,  and  cab- 
bage can  be  raised  to  advantage  on  this  soil.  No  such  specialization  has 
been  brought  about  in  Calvert  County  and  in  consequence  the  Sassafras 
loam  areas  are  not  producing  as  great  a  variety  of  crops  nor  as  large  a 
quantity  of  the  ones  cultivated  as  is  possible. 

The  Sassafras  sandy  loam  is  a  brown  sandy  loam  underlain  by  a 
heavier  loam  subsoil.  It  is  found  only  on  low  terraces  bordering  the 
largest  streams.  This  soil  has  been  one  of  the  most  desired  and  best 
cultivated  types  since  the  earliest  settlement  of  the  county.  Its  location 


MARYLAND   GEOLOGICAL    SURVEY  165 

and  texture  adapt  it  to  general  farming  and  it  ranks  as  a  medium  wheat 
and  corn-producing  soil  capable  of  producing  good  crops  of  clover,  peas, 
and  tobacco.  Good  peach  orchards  are  found  on  it  and  stock  raising  has 
been  undertaken  on  some  of  the  farms  along  the  Patuxent.  The  Sassa- 
fras sandy  loam  presents  a  pleasing  picture  of  the  best  farming  condi- 
tions in  the  county.  The  level  or  slightly  rolling  fields  of  brown,  loamy 
soil  are  thoroughly  cleared  and  carefully  cultivated. 

The  Meadow  areas,  particularly  the  larger  tracts  on  the  low  foreland 
terraces,  need  extensive  underd  raining  to  fit  them  for  either  general  or 
special  farming.  When  properly  drained  they  would  be  well  adapted 
to  the  production  of  wheat  and  grass.  The  expense  involved  in  clearing 
and  draining  these  lands  will  prevent  their  utilization  to  the  best  advan- 
tage until  after  other  more  easily  managed  soil  types  have  been  brought 
to  a  higher  state  of  cultivation. 

It  follows  at  once  from  the  summary  of  the  capabilities  of  the  Calvert 
County  soils,  deduced  from  the  experience  of  other  communities  with 
the  same  or  similar  soils,  that  large  areas  of  Calvert  County  are  not 
producing  to  the  best  advantage,  and  that  the  responsibility  for  this 
condition  does  not  rest  solely  if  at  all  with  the  soil. 

The  soils  of  Calvert  County  were  first  brought  under  cultivation  when 
the  entire  area  farmed  in  the  present  limits  of  the  United  States  con- 
stituted but  a  narrow  fringe  along  the  tidewater  portion  of  the  Atlantic 
seaboard.  They  have  been  tilled  continuously  for  nearly  two  hundred 
and  fifty  years  under  various  conditions  and  with  varying  success.  The 
early  colonists  began  the  cultivation  of  tobacco  to  the  exclusion  of  food 
crops  and  an  early  enactment  of  the  colony  provided  that  two  acres  of 
corn  must  be  planted  for  each  person  in  the  colonist's  family  in  order 
that  they  should  have  a  grain  crop  to  live  upon.  This  indicates  the  extent 
to  which  the  tobacco  crop  held  sway  even  at  the  beginning  of  the  history 
of  the  county.  Calvert  County  in  common  with  the  other  counties  of 
southern  Maryland  remained  a  tobacco-raising  region  of  eminence  for 
nearly  two  centuries.  The  crop  was  cultivated  by  means  of  slave  labor 
and  large  plantations  were  the  rule  rather  than  small  farms.  During 
this  period  the  type  of  tobacco  was  developed  which  has  secured  a  place 


166  THE   SOILS    OF    CALVEKT    COUNTY 

in  the  trade  world  under  the  name  of  Maryland  pipe  tobacco.  This 
tobacco  is  in  demand  for  the  French  export  trade,  and  the  region  is 
called  upon  at  present  to  furnish  from  15,000  to  18,000  hogsheads  of 
about  800  pounds  weight  each  year.  Not  all  of  the  tobacco  produced 
reaches  the  standard  set  by  the  French  market,  and  of  late  years  increas- 
ing quantities  of  Ohio  tobacco  have  come  in  competition  with  the  Mary- 
land product. 

The  Civil  War,  as  in  other  localities,  brought  about  an  entire  change  in 
the  social  and  economic  relationships  of  the  county  and  consequently  in 
its  agricultural  activities.  Many  plantations  which  were  admirably  tilled 
by  large  forces  of  hands  speedily  deteriorated,  since  the  labor  necessary 
for  their  cultivation  could  not  even  be  hired.  The  financial  loss  of  the 
owners,  due  to  the  freeing  of  the  slaves,  was  thus  augmented  by  seasons 
of  enforced  non-production.  The  larger  plantations  were  either  mort- 
gaged heavily,  in  an  effort  to  keep  them  under  cultivation,  or  else  por- 
tions of  them  were  allowed  to  go  out  of  cultivation.  Even  the  sale  of 
land  which  became  superfluous  under  the  new  order  of  affairs  was  diffi- 
cult, since  the  great  majority  of  the  community  suffered  from  the  same 
causes.  At  the  same  time  the  tide  of  western  migration  carried  settlers 
past  the  eastern  seaboard  to  cheap  government  lands  in  the  West  and 
very  few  men  of  means  came  in  from  other  localities  to  aid  in  the  further 
development  of  the  region. 

As  the  western  country  was  settled  its  enormous  grain  crops,  pro- 
duced at  a  minimum  expense  for  fertilizing  and  cultivation,  came  into 
direct  competition  with  the  corn  and  wheat  crops  of  the  East.  Thus 
the  crops  which,  in  the  absence  of  abundant  hand  labor,  could  be  pro- 
duced to  best  advantage  came  upon  a  market  fully  stocked  with  grain 
produced  by  less  costly  methods. 

These  conditions  of  labor  and  of  market  have  tended  to  discourage  and 
dishearten  even  the  most  capable  and  energetic.  On  the  other  hand  the 
natural  advantages  of  climate  and  abundant  food  supply  have  encouraged 
improvidence  on  the  part  of  the  wage-earners  and  laborers.  Where 
the  wants  are  few  and  easily  supplied  the  tendency  toward  energy  of  plan 
and  of  action  is  dwarfed.  Thus  some  of  those  most  in  need  of  advance- 


MARYLAND   GEOLOGICAL    SURVEY  167 

ment  have  contented  themselves  with  a  bare  existence,  when  abundance 
might  follow  from  better  directed  and  more  sustained  efforts. 

The  low  productive  power  of  many  areas  besides  the  one  under  dis- 
cussion may  be  ascribed  to  the  same  general  causes.  Methods  of  agri- 
culture must  be  improved,  the  intensive  rather  than  the  extensive  sys- 
tem of  farming  followed,  a  special  effort  for  the  production  of  special 
crops  undertaken,  and  the  adaptation  of  special  soils  to  special  crops 
must  be  better  understood  and  more  fully  practiced. 

The  large  markets  of  the  East  are  accessible  by  boat  and  rail  com- 
munication. Only  a  single  one  is  at  present  patronized  to  any  extent  by 
the  producers  of  Calvert  County.  Using  the  peach  crop  as  an  example, 
instances  are  known  where  large  and  fine  crops  of  peaches  have  been 
marketed  at  a  loss  on  a  single  market  which  was  glutted,  while  other 
markets  only  little  less  accessible  were  far  from  stocked. 

Such  changes  as  will  enhance  the  value  and  productiveness  of  the 
county  must  come  slowly,  supported  by  the  experience  of  the  most  pro- 
gressive and  best-equipped  inhabitants.  Such  changes  are  in  progress 
and  some  of  them  have  passed  the  experimental  stage.  Others  have  been 
planned  but  not  undertaken,  and  it  is  to  be  hoped  that  increased  knowl- 
edge of  the  conditions  both  within  and  without  the  county  may  enable  its 
inhabitants  to  realize  the  opportunities  which  they  possess  and  from  which 
they  may  profit. 


THE  CLIMATE  OF  CALVERT  COUNTY 


BY 

C.  F.  VON  HERRMANN 


INTRODUCTORY. 

The  object  for  which  the  Maryland  State  Weather  Service  was  or- 
ganized is  to  study  thoroughly  the  climatic  features  of  the  different 
sections  of  Maryland,  to  ascertain  as  far  as  possible  the  effect  of  each 
of  the  controlling  factors,  and  to  publish  the  meteorological 
data  available  in  sufficient  detail  to  enable  students  to  investigate  the 
numerous  problems  of  climate  as  related  to  hygiene,  agriculture,  and 
the  mechanical  arts,  the  solution  of  which  is  important  for  the  welfare 
of  the  people.  Pursuant  to  this  plan,  a  General  Sketch  of  the  Climate 
of  Maryland,  by  Mr.  F.  J.  Walz,  was  published  in  Volume  I  of  the 
Maryland  Weather  Service  Reports,  and  a  full  account  of  the  Weather 
and  Climate  of  Baltimore,  by  Dr.  Oliver  L.  Fassig  appeared  in  Volume  II. 
Chapters  have  also  been  published  on  the  climate  of  three  counties  in 
the  State,  namely  Allegany,  Cecil,  and  Garrett,  and  it  is  intended  ulti- 
mately to  cover  every  county  in  the  State.  Collected  into  one  volume, 
these  county  reports  will  form  an  invaluable  repertory  of  meteorological 
information  for  the  student.  The  excellent  plan  adopted  in  the  first 
sketches  published  has  been  but  slightly  modified  in  the  following  account' 
of  the  climate  of  Calvert  County. 

THE  FACTORS  CONTROLLING  CLIMATE. 

The  climate  of  any  region  depends  primarily  upon  the  following 
chief  factors : 

Latitude;  the  physiographic  features  of  the  region,  especially  its  posi- 
tion with  reference  to  mountains  or  large  bodies  of  water;  to  a  minor 
12 


170  THE    CLIMATE   OF    CALVERT    COUNTY 

degree  on  its  topography,  the  slope  of  the  surface,  whether  valley  or 
mountain  top,  the  nature  of  the  soil  and  soil  covering,  and  lastly,  on  the 
position  of  the  region  with  reference  to  the  prevailing  path  of  storms. 

The  sun's  power  is  greatest  when  the  rays  strike  the  earth's  surface 
vertically,  and  the  highest  temperatures  might  be  expected  to  occur  in 
regions  where  the  sur>  is  overhead  at  noon,  which  can  take  place  only 
within  the  tropics.  The  inclination  of  the  earth's  axis  23£  degrees  from 
the  perpendicular  to  the  plane  of  its  orbit  profoundly  modifies  this 
simple  deduction  by  causing  a  variation  in  the  length  of  the  day  as  the 
pole  is  approached.  During  the  summer  of  the  northern  hemisphere 
the  length  of  the  day  increases  rapidly  from  the  equator  toward  the 
pole,  and  the  increased  duration  of  sunshine  compensates  largely  for 
the  greater,  inclination  of  the  sun's  rays.  Maryland,  lying  between  the 
parallels  of  38°  and  40°  north  Latitude,  at  the  time  of  the  summer 
solstice,  June  21,  has  a  day  of  nearly  15  hours'  duration,  and  the  soil 
and  air  are  able  to  accumulate  a  large  store  of  heat  during  the  long 
summer  day.  The  long  winter  nights  which  favor  the  loss  of  heat  by 
outward  radiation  give  a  sharp  contrast  to  the  different  seasons  which 
is  quite  absent  in  polar  or  tropical  latitudes.  The  factors  which  con- 
trol climate  act  together  in  so  intricate  a  manner  that  it  is  difficult  to 
ascertain  precisely  what  effect  latitude  itself  to  the  exclusion  of  other 
causes  may  have  upon  the  climate  of  a  region,  but  a  rough  way  of  esti- 
mating this  effect  will  be  found  in  the  discussion  of  the  climate  of 
St.  Mary's  County. 

The  position  of  a  country  with  reference  to  mountain  chains  or  to 
large  bodies  of  water  has  a  profound  effect  011  climate.  Over  any  level 
'plain,  even  in  tropical  regions,  the  temperature  decreases  in  free  air  about 
1°  Fahrenheit  for  every  300  feet  increase  of  elevation.  Mountains 
thrust  themselves  up  into  this  region  of  colder  air  and  thus  lower  the 
temperature  of  their  surroundings.  Again,  mountains  have  a  strong 
influence  on  rainfall  by  facilitating  the  ascent  of  moist  air  currents 
flowing  up  their  slopes,  and  so  causing  condensation  and  precipitation  by 
dynamic  cooling.  On  the  other  hand  large  masses  of  water  have  a  con- 
serving influence,  lessening  extremes  of  temperature,  and  their  action 


MARYLAND   GEOLOGICAL    SURVEY  171 

is  so  powerful  as  to  determine  the  difference  between  what  is  called 
continental  and  marine  climates. 

The  valleys  in  a  mountain  region  have  greater  extremes  of  temperature 
than  the  mountain  tops,  being  usually  warmer  during  the  day  and  in 
summer,  and  colder  at  night  and  during  winter,  because  the  cold  air 
flows  down  the  slopes  and  accumulates  in  the  depressions.  The  effect  of 
the  nature  of  the  soil  and  soil  covering  is  also  important.  The  mean 
temperature  of  the  soil  is  always  higher  than  that  of  the  air  above  it. 
There  are  great  differences,  however,  in  the  amount  of  heat  which  differ- 
ent soils  return  to  the  air.  In  rocks  the  temperature  is  higher  at  all 
depths  and  at  all  times  of  the  year  than  in  the  overlying  air,  consequently 
rocky  soils  give  up  more  heat  to  the  air  than  other  kinds.  In  sandy  land 
the  upper  layers  only  are  warmer  than  air,  while  moist  lands  or  bogs 
are  colder  because  much  of  their  heat  is  lost  in  causing  evaporation. 
A  covering  of  vegetation  lowers  the  temperature  of  the  soil,  and  changes 
in  temperature  over  grass  and  forests  are  less  than  over  bare  soils.  In- 
cidentally forests  conserve  the  rainfall,  returning  it  slowly  to  the  streams 
and  diminishing  the  evil  effects  of  drought. 

The  position  of  a  place  with  reference  to  the  prevailing  path  of 
storms  determines  the  frequency  of  rainy  days,  the  cloudiness,  the  winds, 
and  all  the  variable  phenomena  called  weather,  which  are  non-periodic 
in  occurrence. 

THE    PHYSIOGRAPHIC    FEATURES    OP    CALVERT    COUNTY. 

In  order  to  correctly  interpret  the  climate  of  Calvert  County  it  is 
essential  to  have  some  knowledge  of  its  physiographic  features,  but  as 
complete  details  will  be  found  in  other  portions  of  this  volume,  it  will 
only  be  necessary  to  give  here  a  brief  recapitulation  of  the  main  facts. 

Geologists  divide  the  region  from  the  Appalachian  chain  to  the  Atlan- 
tic coast  into  three  well-known  physiographic  provinces :  the  Appalachian 
Eegion,  Piedmont  Plateau,  and  Coastal  Plain.  In  Maryland  the  Coastal 
Plain  includes  all  that  portion  of  the  State  lying  east  of  a  line  extending 
from  southwest  to  northeast  through  Washington,  Baltimore,  and  Wil- 
mington, Del.,  or  about  one-half  the  area  of  the  State.  The  Coastal 


172  THE   CLIMATE   OF    CALVERT    COUNTY 

Plain  is  divided  into  two  portions  by  Chesapeake  Bay,  the  higher  western 
division  being  known  as  Southern  Maryland.  It  includes  St.  Mary's, 
Calvert,  Charles,  Prince  George's,  and  Anne  Arundel  counties. 

The  characteristics  of  the  Coastal  Plain,  important  from  a  climatic 
standpoint,  are  its  low,  level  lands,  composed  mostly  of  unconsolidated 
sands  and  clays,  and  the  deep  indentation  of  the  region  by  Chesapeake 
Bay,  its  rivers  and  tributaries.  The  elevation  of  the  land  is  consider- 
ably higher  in  the  western  peninsula  than  in  eastern  Maryland,  fre- 
quently exceeding  100  feet  even  along  its  eastern  margin,  and  reaching 
280  feet  farther  west  near  Washington.  Calvert  County  extends  in  its 
greatest  length  north  and  south,  and  lies  between  the  Patuxent  Eiver 
and  Chesapeake  Bay.  The  water-shed  of  the  county  has  the  peculiarity 
of  being  near  the  eastern  shore,  so  that  the  drainage  of  the  region  is 
largely  southwest  into  the  Patuxent  River.  In  southern  Calvert  County 
an  elevation  of  140  feet  is  found  to  the  west  of  Cove  Point,  and  there 
is  a  gradual  increase  in  elevation  northward  to  the  southern  border  of 
Anne  Arundel  County  where  the  land  rises  above  180  feet. 

The  soils  of  Calvert  County  belong  chiefly  to  the  Pleistocene  forma- 
tions. They  are  undoubtedly  of  comparatively  recent  elevation  above 
sea  level,  and  are  composed  of  unconsolidated  sands,  gravels,  and  clays. 
The  proportion  of  clay  is  often  less  than  3  per  cent,  and  the  soils  are 
accordingly  not  very  retentive  of  moisture ;  they  must  therefore  be  warm, 
and  able  to  force  vegetation  to  early  maturity,  and  would  probably 
make  fine  truck  farms  under  modern  methods  of  intensive  cultivation. 
Pine  barrens  occupy  a  considerable  area  in  Calvert  County. 

It  will  be  seen  from  this  brief  description  of  the  physiographic  features 
of  the  county,  that  the  chief  modifying  factor  is  the  presence  of  large 
bodies  of  water,  in  Chesapeake  Bay,  Patuxent  River  and  its  tributaries, 
and  the  Atlantic  Ocean,  distant  only  about  75  miles  eastward.  Eleva- 
tion plays  no  important  role.  It  would  seem  proper  in  this  sketch  to 
give  some  attention  to  the  general  influence  of  water  masses  on  climate 
and  to  seek  to  ascertain,  as  far  as  the  data  available  will  permit,,  what 
specific  effect  must  be  attributed  to  the  proximity  of  the  Bay  and  the 
Atlantic  Ocean. 


MARYLAND   GEOLOGICAL   SURVEY  173 

THE  INFLUENCE  OF  WATER  ON  THE  DISTRIBUTION  OF  TEMPERATURE. 

Over  all  land  surfaces  the  temperature  of  the  air  is  determined  by 
the  temperature  of  the  soil,  and  the  modifying  effects  of  large  bodies 
of  water  on  temperature  depends  on  the  differences  in  the  effect  of  solar 
radiation  on  land  and  water.  These  differences  are  very  striking.  Since 
the  specific  heat  of  soil  is  low  (about  0.6  calories)  it  is  readily  warmed, 
but  as  it  is  opaque  and  a  relatively  poor  conductor  of  heat  the  insolation 
acts  on  a  relatively  thin  surface  layer.  Soil  is  a  solid  substance  and 
therefore  cannot  equalize  temperature  differences  by  movements  within 
itself;  it  is  a  poor  reflector  and  does  not  turn  away  much  of  the  radia- 
tion incident  upon  it;  there  is  no  loss  of  heat  in  causing  evaporation. 
These  conditions  all  combine  to  produce  great  heat  in  a  relatively  thin 
top  layer  of  soil  under  direct  sunshine,  and  a  rapid  loss  of  heat  by  radia- 
tion at  night,  making  for  great  contrasts  in  the  temperature  of  the  soil 
and  of  the  air  above  it. 

Consider  the  case  with  reference  to  water.  The  specific  heat  of  water 
is  very  high;  there  is  no  other  natural  substance  known1  which 
requires  so  much  heat  to  raise  its  temperature,  and  therefore  a  given 
mass  of  water  is  warmed  with  much  greater  difficulty  than  an  equal  mass 
of  soil.  Water  is  cooled  with  equal  difficulty.  Much  of  the  insolation 
on  a  water  surface  is  reflected  away,  and  that  which  does  enter  the  water 
penetrates  to  great  depths  so  that  the  heat  is  more  uniformly  diffused. 
The  water,  being  mobile,  changes  in  temperature  produce  convectional 
currents  and  the  winds  produce  surface  currents,  both  of  which  tend 
constantly  to  mix  the  warmed  water  with  cooler  portions  and  thus  to 
moderate  the  rise  in  temperature.  Lastly  much  of  the  heat  incident 
upon  a  water  surface  is  expended  in  changing  some  of  the  water  from 
the  liquid  state  to  vapor,  an  operation  which  causes  a  large  amount  of 
heat  to  become  latent.  The  consequences  of  these  conditions  are  that 
water  becomes  very  slowly  warmed  and  throughout  a  considerable  mass, 
and  that  it  cools  only  slowly  when  insolation  is  withdrawn,  making  for 
slight  contrasts  in  the  temperature  of  the  water  and  of  the  air  above  it. 
The  proximity  of  large  bodies  of  water  must  modify  the  temperature  of 

1  Liquid  hydrogen  has  a  specific  heat  6.0  calories.   (Dewar.) 


174 


THE    CLIMATE   OF    CALVERT    COUNT! 


a  region  by  lessening  the  extremes  both  of  summer  heat  and  winter  cold, 
especially  the  latter.2 

Viewing  more  closely  the  relative  temperatures  of  air  and  water,  it 
is  found  that  in  tropical  oceans  the  temperature  of  the  water  is  always 
higher  than  the  temperature  of  the  air  above  it.  In  middle  latitudes 
the  water  is  slightly  cooler  than  the  air  during  the  warmest  portion  of 
the  day.  The  hourly  temperature  of  the  waters  of  the  north  Atlantic 
Ocean  about  the  latitude  of  southern  Maryland  are  given  in  the  follow- 
ing table,  which  also  shows  the  extent  to  which  the  air  above  is  warmer 
or  colder  than  the  water,  and  the  extremely  small  range  of  both. 


HODHLY  TEMPERATURES  OF  THE  SURFACE  WATERS  OF  THE  NORTH  ATLANTIC  OCEAX  AND 
OF  THE  AIR  ABOVE  (HANN). 


Time  | 

1 
A.  M. 

3 
A.M. 

5 
A.  M. 

7     I     9 
A.  M.  A.  M. 

11 
A.  M. 

1 
P.  M. 

3 
P.  M. 

5 
P.  M. 

7 
P.  M. 

9 
P.  M. 

11 
P.  M. 

Means. 

Water  

67.6 

67.5 

67.6 

67.6 

68.0 

68.2 

68.2 

68.4 

68.2 

68.0 

67.8 

67.6 

67.8 

Air 

66  0 

66  0 

66  ° 

66  5 

67  3 

68  4 

69  1 

69  1 

68  5 

67  5 

66  7 

66  2 

67  3 

Difference.... 

-1.6 

-1.5 

-1.4 

-1.1 

-0.7 

+0.2 

+0.9 

+0.7 

+0.3 

-0.5 

-1.1 

—1.4 

-0.5 

The  monthly  mean  temperature  of  the  surface  waters  of  the  Atlantic 
Ocean  are  also  generally  above  the  mean  temperature  of  the  overlying  air 
except  where  cold  ocean  currents  prevail. 

The  effect  of  the  oceans  in  mitigating  temperatures  is  nowhere  more 
strikingly  shown  than  on  the  west  coast  of  Europe.  England,  which  lies 
on  the  same  parallel  as  inhospitable  Labrador,  has  a  climate -proper  to  a 
latitude  20  degrees  farther  south.  This  is  due,  not  to  the  higher  tem- 
perature of  the  Gulf  stream  itself,  but  to  the  modifying  influence  of 

2  It  may  perhaps  be  well  to  show  by  a  numerical  calculation  the  amount 
of  heat  given  up  to  the  air  by  water  in  cooling.  The  amount  of  heat  required 
to  warm  one  cubic  centimeter  of  air  1°  C.  is  only  0.00031  calories;  therefore 
the  specific  heat  of  air  is  3257  times  smaller  than  that  of  water.  If  a  surface 
layer  of  water  1  centimeter  thick  cools  one  degree,  the  quantity  of  heat 
liberated  would  raise  the  temperature  of  a  mass  of  air  33  meters  thick  1°  C. 
When  water  freezes  a  large  additional  quantity  of  heat  is  given  up  to  the 
air.  (Hann.) 


MARYLAND   GEOLOGICAL    SURVEY  175 

the  ocean  exerted  through  the  medium  of  the  prevailing  winds.  The 
effect  of  the  winds  is  extremely  important.  The  west  coast  of  Europe  is 
subjected  to  the  prevailing  westerlies  resulting  from  the  circulation  of 
air  about  the  permanent  low  pressure  area  in  the  vicinity  of  Iceland, 
which  brings  the  air  from  the  ocean  over  the  land.  The  conditions  on 
the  eastern  coast  of  the  United  States  are  quite  different.  We  have  the 
ocean  before  us,  but  it  cannot  exert  its  full  influence  because  the  pre- 
vailing winds  are  still  from  the  west,  from  the  land  towards  the  sea. 
In  winter  the  North  American  continent  is  covered  by  an  area  of  high 
pressure  out  of  which  air  flows  in  all  directions,  giving  Maryland  its 
prevailing  northwest  winds  during  the  colder  season  of  the  year.  In  sum- 
mer, it  is  true,  the  same  region  is  occupied  by  low  pressure,  but  the  main 
pathway  of  moving  depressions  being  the  Lake  region  and  St.  Lawrence 
valley,  Maryland  is  in  such  position  as  to  receive  chiefly  southwesterly 
winds  in  summer,  which  are  also  off  shore.  At  some  stations  southeast 
winds  are  found  to  prevail  in  early  summer,  but  they  are  of  feeble 
character  and  do  not  transport  air  over  the  land  from  any  great  extent 
of  ocean  surface.  Consequently  the  waters  of  Chesapeake  Bay  and  the 
Atlantic  Ocean  cannot  exert  on  the  climate  of  Maryland  the  same  marked 
influence  which  gives  western  Europe  its  mild  climate,  and  Maryland,  as 
well  as  all  other  States  of  the  north  Atlantic  coast,  retains  a  climate  sub- 
jected to  great  extremes,  that  is  mainly  continental  in  character. 

In  addition  it  must  be  observed  that  the  Gulf  stream  is  separated  from 
the  coast  of  America,  at  least  as  far  south  as  Hatteras,  by  the  cold 
Labrador  current,  which  undoubtedly  lowers  the  temperature  of  the 
waters  of  the  Atlantic  near  the  coast  below  the  normal.  Eeferring  to 
the  interior  mass  of  water  known  as  Chesapeake  Bay,  it  appears  probable 
that  its  temperature  is  also  below  the  normal,  since  it  receives  a  large 
supply  of  cold  water  from  melting  snows  and  cold  springs  in  the  western 
mountains,  through  the  Susquehanna,  Potomac,  and  other  rivers.  This 
view  is  confirmed  by  the  series  of  observations  on  the  temperature  of  the 
water  surface  in  the  harbor  of  Baltimore  from  1882  to  1886,  published 


176 


THE    CLIMATE   OF    CALVERT    COUNTY 


in  the  report  on  the  Climate  and  Weather  of  Baltimore  and  Vicinity.3 
The  monthly  average  temperature  of  the  water  in  the  harbor,  and  of  the 
air  above  it,  is  reproduced  here  in  Table  II,  and  for  comparison  the  mean 
temperature  of  the  waters  of  the  north  Atlantic  about  Lat.  35°  N".,  and 
Long.  0°  to  50°  W. 

TABLE    II. 

TEMPERATURE  OF  THE  WATEK  IN  BALTIMORE  HAHBOR,  OF  THE  Ain,  AND  OF  THE  SURFACE 
OF  THK  ATLANTIC,  LAT.  35  N. 


Jan. 

Feb. 

Mar. 

Apr. 

May 

June 

July 

Aug.  Sept. 

Oct. 

Nov. 

Dec. 

Year 

Air  

36.4 

40.7 

46.8 

58.7 

68.4 

79.1 

83.0 

80.3 

76.2 

64.8 

51.3 

40.1 

60.2 

Water  

34.8 

36.5 

40.1 

51.4 

62.1 

73.4 

78.3 

78.3 

74.0 

66.2 

62.4 

39.8 

67.1 

Difference  

-0.6 

-6.2 

-6.7 

-7.3 

-6.3 

-6.7 

—4.7 

-2.0 

—1.2 

+0.4 

+1.1 

-0.3 

-3.1 

N.  Atlantic  

63.3 

62.1 

62.6 

63.5 

66.7 

69.1 

72.9 

76.2  |  73.8 

71.6 

67.6 

65.1 

67.7 

The  temperature  of  the  water  in  Baltimore  harbor  is  lower  than  the 
temperature  of  the  overlying  air  except  in  late  autumn,  when  the  tem- 
perature of  the  land  is  falling  more  rapidly  than  the  temperature  of  the 
water,  while  in  the  ocean  eastward  in  the  same  latitude  the  water  is 
always  warmer  than  the  air.  The  greatest  difference  is  found  during 
spring  and  early  summer;  during  April,  May,  and  June,  the  water  is 
nearly  6°  colder  than  the  air,  and  it  is  least  in  winter  when  the  dif- 
ference nearly  vanishes.  The  effect  of  the  water  in  lessening  extremes 
of  temperature  near  the  coast  in  summer  is  much  diminished  in  conse- 
quence of  the  fact  that  warm  periods  are  usually  associated  with  a  stag- 
nant atmosphere  (very  light  winds)  due  to  the  encroachment  of  the  per- 
manent high  pressure  area  about  Lat.  30°  on  the  southeast  coast  of  the 
United  States;  so  it  is  found  that  even  in  Calvert  County  high  summer 
temperatures  sometimes  exceeding  100°  are  recorded. 

3 Report  on  The  Climate  and  Weather  of  Baltimore  and  Vicinity;  by  Dr. 
Oliver  L.  Fassig,  vol.  ii,  part  la,  page  146.  The  temperature  of  the  water 
was  taken  at  2  p.  m.  when  it  is  normally  a  little  cooler  than  the  air  (see 
Table  I)  but  the  departures  in  this  case  are  so  great  as  to  substantiate  the 
conclusion  in  the  text  that  the  harbor  waters  are  abnormally  cold.  No 
doubt  the  mean  temperature  of  the  water  from  tridaily  observations  would 
prove  to  be  higher  than  the  temperature  of  the  air  during  October,  November. 
December,  and  January. 


MARYLAND   GEOLOGICAL    SURVEY  177 

The  effect  of  the  proximity  of  the  ocean  and  Bay  on  the  amount  of 
precipitation  in  Calvert  County  is  comparatively  slight.  It  is  true  that 
the  air  contains  more  moisture  than  the  interior  regions,  but  the  country 
is  flat  and  cannot  cause  upward  deflection  of  the  winds  and  consequent 
cooling  by  means  of  which  condensation  is  chiefly  brought  about.  The 
precipitation  in  Calvert  County  is  less  than  in  counties  northward  on  the 
same  meridian,  but  slightly  more  than  in  some  interior  counties.  When 
local  storms  occur  in  which  ascending  air  currents  are  produced  by 
strictly  dynamic  causes,  the  abundance  of  moisture  is  such  as  to  make 
very  heavy  rainfalls  possible  over  limited  areas,  such,  for  instance,  as 
occurred  at  Jewell,  July  26  and  27,  1897,  when  14.75  inches  fell  in  less 
than  24  hours. 

Calvert  County  is  too  far  from  the  Appalachian  mountains  to  be 
directly  influenced  by  them,  though  sharing  with  other  portions  of  the 
State  in  the  protection  afforded  by  the  mountain  barrier  to  the  sweep 
of  cold  waves  from  the  west.  At  the  same  time  the  prevailing  north- 
west winds  of  winter  must  necessarily  bring  down  to  the  level  of  the 
Coastal  Plain  the  colder  bracing  air  of  the  mountains,  thus  counteracting, 
as  before  stated,  the  effects  of  neighboring  water  surfaces  and  emphasiz- 
ing the  continental  character  of  our  climate. 

METEOROLOGICAL  DATA  AVAILABLE  FOR  CALVERT  COUNTY. 

The  meteorological  data  available  for  Calvert  County  are  unfortu- 
nately very  limited.  Only  two  co-operative  stations  have  ever  existed  in 
the  county,  both  of  which  are  still  in  operation.  Prince  Fredericktown 
was  established  February  1,  1899,  by  the  Maryland  State  Weather  Ser- 
vice with  Mr.  Alfred  Presson  as  observer.  The  instruments  are  private 
property  but  are  of  standard  pattern,  and  are  exposed  about  2  miles 
north-northeast  of  Calvert  County  court  house,  Lat.  38°  34'  N.,  Long. 
76°  35'  W.,  at  an  elevation  of  about  80  feet  above  sea  level.  This  series 
of  observations  is  very  much  broken  and  no  record  for  an  entire  year 
exists. 

The  only  other  station  in  the  county  is  Solomons,  situated  on  an 
island  at  the  extreme  southern  point  of  the  county.  Under  the  auspices 


178  THE    CLIMATE   OF    CALVERT    COUNTY 

of  the  Maryland  State  Weather  Service  .observations  were  begun  at 
Solomons  by  Dr.  William  Henry  Marsh  in  January,  1892,  and  have  been 
continuous  since  that  date.  The  latitude  of  the  station  is  38°  19'  N., 
longitude  76°  27'  W.,  and  elevation  about  20  feet  above  sea  level.  The 
series  of  observations  by  Dr.  Marsh  are  admirable  in  every  respect,  and 
must  long  serve  as  the  criterion  for  the  comparison  of  other  records  in 
southern  Maryland.  By  his  faithful  persistence  during  a  period  of  14 
years  Dr.  Marsh  has  performed  a  highly  commendable  service  in  the 
interest  of  science.  It  is  proposed  to  publish  the  record  for  Solomons  in 
as  complete  a  form  as  possible. 

In  order,  however,  to  obtain  approximately  correct  mean  values  of 
temperature  and  precipitation  for  the  county  at  large,  recourse  must  be 
had  to  the  data  of  neighboring  stations.  The  means  for  the  county  may 
be  obtained  with  a  close  approach  to  accuracy  by  making  use  of  the  fol- 
lowing records:  Solomons  (length  of  record  14  years)  at  the  southern 
extremity  of  the  county,  Cambridge  (7  years)  east  of  Chesapeake  Bay  in 
Dorchester  County,  about  the  same  latitude  as  Prince  Frederick,  Jewell 
(15  years)  at  the  northern  border  in  Anne  Arundel  County,  and 
Charlotte  Hall  (9  years)  west  of  the  central  portion  of  the  county  in 
St.  Mary's  County. 

TEMPERATURE  CONDITIONS. 

The  average  temperature  conditions  for  Calvert  County  are  given  in 
Table  III.  The  first  portion  of  the  table  gives  the  actual  means  and 
extremes  at  all  stations;  as  the  periods  of  observation  are  relatively 
short,  it  would  not  be  correct  to  assume  that  any  of  the  records  give  true 
normals  of  temperature.  A  correction  has  therefore  been  applied  to 
each  station,  the  amount  of  which  was  determined  by  comparison  with 
the  Baltimore  record  for  88  years  from  1817  to  1905.  The  averages  of 
the  corrected  means  for  Cambridge,  Charlotte  Hall,  Jewell,  and  Solo- 
mons may  be  considered  to  give  a  fairly  accurate  normal  mean  tempera- 
ture for  Calvert  County. 


MARYLAND   GEOLOGICAL    SURVEY 


179 


180  THE    CLIMATE   OF    CALVERT    COUNTY 

The  annual  mean  temperature  of  Calvert  County  is  found  to  be  56.8°. 
This  mean  is  probably  exceeded  only  at  stations  in  St.  Mary's  County 
and  in  the  extreme  southern  counties  of  the  Eastern  Shore.  Spring  has 
a  temperature  of  55°,  summer  77°,  autumn  59°,  and  winter  37°. 
Autumn  is  4°  warmer  than  spring.  The  warmest  month  is  July  with  a 
mean  temperature  of  78°,  and  the  coldest  is  January  with  a  mean  of  36°. 
It  will  be  of  interest  to  compare  these  temperatures  with  similar  data  for 
Garrett  County,  the  coldest  in  Maryland : 

Annual  Warmest                               Coldest 

County                                            Mean  Month                                  Month 

Garrett 47.0°  68°  in  July  24°  in  February 

Calvert 56.8°  78°  in  July  36°  in  January. 

Garrett  County  is  much  colder  chiefly  on  account  of  its  far  greater  ele- 
vation above  sea  level.  The  temperature  rises  most  rapidly  from  April 
to  May  (difference  in  means  10°)  and  as  the  sun  declines  after  reaching 
its  highest  point  a  comparatively  slow  fall  in  temperature  occurs  until 
after  the  autumnal  equinox  when  it  becomes  very  rapid,  so  that  the 
difference  between  the  September  and  October  means  is  over  12°. 

The  extremes  in  Calvert  County  are,  maximum  103°,  minimum  5° 
below  zero,  both  at  Solomons.  The  maximum  is  the  highest  temperature 
recorded  in  the  county,  but  at  Charlotte  Hall  a  minimum  of  19°  below 
zero  occurred  in  February,  1899,  and  it  is  probable  that  similar  low 
temperatures  were  felt  in  the  northern  portion  of  Calvert  County.  Both 
of  these  extremes  have  been  exceeded  in  other  counties  of  Maryland.  The 
highest  temperature  officially  recorded  for  the  State  is  109°,  July  3, 

1898,  at  Boettcherville,  near  Cumberland,  Allegany  County.     The  lowest 
temperature  ever  recorded  in  Maryland  was  26°  below  zero  February  10, 

1899,  at  Sunnyside  in  Garrett  County.     The  monthly  mean  temperature 
has  exceeded  80°  on  rare  occasions  at  stations  in  Calvert  and  neighboring 
counties.     The  highest  mean  was  82.7°  at  Solomons,  August,  1900.    The 
lowest  monthly  mean  was  24.6°  at  Jewell  in  January,  1893.     This  gives 
a  possible  range  in  monthly  mean  temperatures  of  58°,  a  fact  which  suffi- 
ciently  emphasizes   the   continental   character   of   the   climate   of   this 
region. 


MARYLAND   GEOLOGICAL   SURVEY  181 

PRECIPITATION. 

Precipitation  is  an  extremely  variable  element  of  climate,  and  very 
great  differences  may  be  found  at  stations  not  widely  separated;  no 
corrections  can  be  applied  to  short  records  of  rainfall,  and  the  averages 
for  the  county  have  been  obtained  from  the  original  uncorrected  records 
as  given  in  Table  IV.  A  critical  examination  of  the  records  will  lead  to 
the  conclusion  that  probably  the  amounts  at  Cambridge  and  Jewell  are 
slightly  above  the  true  normals  for  the  region,  while  at  Charlotte  Hall 
they  are  below. 

Calvert  County  receives  slightly  over  42  inches  of  rain  per  annum. 
While  this  amount  is  slightly  less  than  that  for  most  other  counties 
farther  north,  it  is  not  the  lowest  value  in  Maryland,  which  appears  to 
obtain  in  Allegany  County,  approximately  34  inches  per  annum.4  As  in 
all  other  counties  of  Maryland  the  precipitation  is  quite  uniformly  dis- 
tributed throughout  the  year.  The  greatest  average  occurs  in  July,  with 
5.32  inches,  which  is  13  per  cent  of  the  annual  total;  and  the  least  occurs 
in  November  with  2.45  inches,  which  is  6  per  cent  of  the  annual  amount. 
Excessive  precipitation  is  not  frequent  in  Calvert  County.  A  monthly 
total  of  10.00  inches  may  be  considered  excessive  for  the  region  under 
discussion.  No  monthly  total  approaching  this  amount  has  been  re- 
corded at  either  Cambridge,  Charlotte  Hall,  or  Solomons.  At  Jewell, 
however,  which  is  quite  near  the  northern  boundary  of  Calvert  County, 
an  amount  exceeding  10  inches  has  occurred  three  times  during  the  past 
15  years,  namely  in  July,  1889  (10.25  inches) ,  July,  1891  (12.15  inches), 
and  July,  1897  (19.90  inches).  At  all  stations  amounts  less  than  1.00 
inch  are  not  infrequent,  and  at  Jewell  only  a  "  trace  "  was  received  in 
December,  1889.  The  absence  of  rainfall  during  an  entire  month  is 
certainly  a  condition  usually  associated  only  with  the  arid  regions  of  the 
West.  The  summer  rainfall  is  heaviest  in  consequence  of  the  greater 
frequency  of  thunderstorms  during  that  season;  spring  follows,  while 
autumn  is  the  driest  season  of  the  year. 

Data  are  not  available  for  finding  the  averages  of  other  climatic  ele- 

4  The  Climate  of  Allegany  County,  by  O.  L.  Fassig,  p.  225. 


182  THE    CLIMATE   OF    CALVERT    COUNTY 

ments  for  Calvert  County.  The  excellent  series  of  observations  taken 
at  Solomons  from  1892  to  1905  fairly  represents  the  conditions  prevail- 
ing in  southern  Maryland,  and  the  reader  is  referred  for  further  details 
to  the  subjoined  account  of  the  climatology  of  Solomons. 

THE  CLIMATOLOGY  OF  SOLOMONS. 

Lat.  38°  19'  ¥. ;  Long.  76°  27'  W. ;  elevation  20  feet.     Eecord  1892-1905. 
Observer,  Dr.  William  Henry  Marsh. 

INTRODUCTORY. 

The  station  is  located  on  Solomons  Island,  in  the  Patuxent  River, 
at  the  southern  extremity  of  Calvert  County.  The  island  contains  about 
40  acres  of  land,  and  its  greatest  elevation  above  mean  tide  is 
not  over  20  feet.  The  nearest  point  on  the  mainland  is 
300  yards  from  the  northwest  end  of  the  island.  The  instruments  are 
located  on  the  east  side,  about  135  feet  from  the  shore  at  low  tide.  The 
exposure  is  an  open  one.  The  nearest  forests  are  distant  2  miles  on 
the  north  and  about  3  miles  south  of  station.  The  elevation  of  the 
nearest  main  land  is  about  the  same  as  that  of  the  island. 

The  thermometers  are  exposed  in  a  standard  shelter  which  is  placed 
20  feet  from  the  house,  over  sod,  and  the  door  of  the  shelter  opens  towards 
the  southeast.  The  thermometers  are  5£  feet  above  the  ground.  The  top 
of  the  raingage  is  3^  feet  above  the  ground,  and  the  nearest  object  is  a 
tree  22£  feet  distant. 

The  climatic  data  available  for  Solomons  are  presented  in  complete 
detail  in  Tables  V  to  XVII.  The  monthly  means  have  been  obtained  in 
all  years  from  the  means  of  the  maximum  and  minimum  temperatures. 
Table  V  gives  the  annual  summaries  at  the  station  from  1892  to  1905, 
and  enables  one  to  study  readily  the  variation  in  the  meteorological  con- 
ditions from  year  to  year,  while  the  footings  of  Tables  VI  to  XVII  show 
the  averages  and  extremes  of  the  most  important  elements  of  climate  for 
each  month  of  the  year.  In  the  text  reference  will  be  made  only  to  the 
most  striking  features  of  climate  with  some  comparison  of  conditions 
at  other  places  in  Maryland. 


MARYLAND   GEOLOGICAL   SURVEY 


183 


TEMPERATURE  CONDITIONS. 

Temperature  is  certainly  the  most  important  of  all  the  climatic  ele- 
ments since  changes  of  temperature  are  the  primary  cause  of  all  move- 
ments in  the  atmosphere  and  of  the  condensation  of  moisture  into  clouds 
and  rain.  Animals  and  plants  are  dependent  for  life  on  a  range  of 
temperature  within  certain  definite  limits,  and  even  man  is  more  or  less 
favorably  or  adversely  affected  in  almost  every  occupation  of  life.  The 
most  important  facts  in  regard  to  temperature  are  most  briefly  expressed 
by  the  monthly  and  annual  means.  These  will  be  found  in  Table  VI. 
The  highest  and  lowest  monthly  means  during  the  entire  period  of  obser- 
vations have  been  selected  to  show  the  possible  variations  from  normal 
conditions. 

TABLE    VI. 

MONTHLY  AND  ANNUAL  MEAN  TEMPERATURES  AT  SOLOMONS  FROM  1892  TO  1905. 
Record  of  Dr.  Wm.  H.  Marsh. 


Year. 

1 

,0 

£ 

March. 

.-4 

'£ 
p. 
•3 

i 

$ 

1-5 

>> 

~5 
>~> 

August. 

I 

i 

I 

1 

< 

1892  
1893  
1894  

31.8 

26.2 
40.8 
34.7 
34.9 
33.2 
38.3 
35.2 
38.0 
37.2 
32.8 
34.6 
30.2 
31.4 

34.2 

37.2 
36.4 
37.7 
27.4 
37.4 
37.4 
36.4 
28.9 
35.4 
32.2 
30.4 
38.9 
29  7 
27^8 

33.8 

37.6    51.0 
42.2    64.8 
48.8    53.0 
43.2     53.9 
40.1     55.8 
46.3    53.9 
48.4     51.8 
42.3    52.6 
41.0     63.8 
45.0     61.1 
46.2     53.6 
49.6    55.0 
42.6     51.1 
45.3    54.6 

44.2     53.3 

64.7 
63.4 
67.7 
62.6 
69.8 
62.4 
64.0 
65.4 
65.6 
62.7 
65.8 
65.6 
65.1 
66.5 

65.1 

77.6 
74.0 
74.9 
76.0 
73.8 
71.6 
74.0 
76.1 
75.0 
72.8 
72.4 
68.4 
72.8 
73.6 

78.2 
78.2 
79.4 
75.8 
78.9 
78.B 
79.0 
79.0 
81.4 
81.0 
78.2 
77.8 
76.6 
77.8 

78.7 
77.4 
75.8 
80.2 
•19.0 
76.8 
79.8 
77.8 
82.7 
78.4 
r,5.2 
74.6 
75.4 
75.7 

69.2 
70.0 
73.8 
75.6 
71.0 

?1 
i4.4 

71.4 

77.0 
71.0 
69.6 
70.1 
71.4 
70.9 

72.0 

68.0 
60.4 
60.9 
56.4 
57.4 
61.1 
61.7 
62.5 
65.3 
59.8 
62.0 
59.2 
57.6 

60.2 

46.4 
47.2 

46.8 
49.6 
53.4 
411.9 
47.3 
50.7 
52.8 
44.0 
54.3 
44.6 
45.6 

J± 

48.7 

36.0 
41.4 
40.6 
40.1 
38  4 
40.0 
37.9 
40.8 
40.7 
36.  R 
37.8 
34.0 
33.7 
38.6 

38.3 

55.6 
56.0 
58.4 
66.3 
57.5 
57.0 
57.8 
56.9 
59.1 
56.0 
56.5 
56.0 
54.3 
55.9 

56.7 

1895  
1896. 

1897  

1898. 

1899  

1900.. 

1901  
1902  

1903. 

1904  
1905  

Means  

73.8 

78.6 

77.7 

Highest  Means  ... 
Lowest  Means  — 
Range  

40.8 
26.2 
14.6 

2.8 

38.9 
27.4 
11.5 

3.8 

49.6 
37.6 
12.0 

2.9 

55.8 
61.0 

4.8 

69.8 
62.4 
7.4 

77.5 
68.4 
9.1 

1.6 

81.4 

75.8 
6.6 

1.0 

82.7 
74.6 
8.1 

|-U 

77.0 

I'.S 

65.3 
66.4 
8.9 

54.3 
44.0 
10.3 

2.9 

41.4 

33.7 

7.7 

2.1 

69.1 
54.3 
4.8 

Mean  Anomalies* 

1.8 

1.5 

1.9 

1.9 

1.0 

*  The  mean  departures  of  the  monthly  meane,  regardless  of  signs. 


184 


THE    CLIMATE   OF    CALVERT    COUNTY 


TABLE  V.-ANNt 
Station,  Solomons,  Calvert  County,  Maryland.    Observer,  Dr.  William  Henry  Mai 


Data                                  Years  j- 

1892 

1893 

'1894 

1895 

1896 

1897 

Annual  Mean  Temperature  

55.5 
61.1 
78.1 
67.9 

78.7,  Aug. 
31.8,  Jan. 
46.9 
98,  July  26 
10,  Jan.  6t 
88 

56.0 
53.5 
76.5 
59.2 
32.9 
78.2,  July 
26.2.  Jan. 
52.0 
95,  June  20 
4,  Jan.  16t 
91 
34,  April  27 
64.4  ' 
47.6 
86.8,  July 
18.6,  Jan. 
16.8 
15 
74 
Nov.l 
April  27 
41.90 
10.42 
9.88 
12.11 
8.62 
4.88,  Oct. 
1.53,  Jan. 
2.60,  Nov.  8 
115 

13,  Mar.  25- 
Apl.  6 
5,  Feb.  9-13 

26.5 
7.5,  Dec. 
7.5,  Dec.  6 
19 

N&NW 
100 
84 
181. 
SE 
41 

58.4 
56.5 
76.7 
60.5 
40.0 
79.4,  July 
37.7,  Feb. 
41.7 
98,  July  29 
11,  Dec.  29 
87 
32,  Mar.  22 
66.4 
50.3 
88.4,  July 
30.5.  Feb. 
16.1 
18 
46 
Nov.  12 
March  28 
32.14 
9.96 
6.07 
8.66 
9.65 
4.65,  May 
0.87,  June 
2.37,  May  18 
115 

13,  Feb.  27- 
Mar.  12 
6,  May  16-20 

13.1 
8.8,  Feb. 
6.0,  Feb.  25 
19 
NE 
100 
92 
173 
NW&  SE 
66 

56.3 
63.2 
77.3 
60.5 
34.2 
80.2,  Aug. 
27.4,  Feb. 
62.8 
100,  May  9 
3,  Feb.  8 
97 
38,  May  9 
64.8 
47.8 
90.0,  Aug. 
19.1,  Feb. 
17.0 
34 
71 
Nov.  3 
March  29 
36.17 
13.27 
10.11 
6.31 
7.95 
5.52,  April 
0.76,  Sept. 
2.00,  June  30 
103 

17,  Oct. 
14-30 

7,  April  27- 
May3 
31.5 

16.0,  Jan. 
7.0,  Jan.  9 
19 

NE 
115 
79 
171 
NW&SE 
48 

57.5 
55.2 
77.2 
60.6 
37.5 
79.0,  Aug. 
34.9,  Jan. 
44.1 
98,  Aug.  12 
11,  Jan.  6t 
87 
31,  May  9t 
65.7 
49.3 
88.6,  Aug. 
28.1,  Jan. 
16.4 
26 
69 
Nov.  14 
April  9 
34.80 
8.24 
10.93 
6.73 
9.72 
6.44,  Feb. 
0.92,  Dec. 

3.75,  Feb. 
6-6 
102 

17,  Jan. 
1-16 
6,  May 
18-23 
4.9 

2.0,  Nov. 
2.0,  Nov.  30 
21 
N 
107 
75 
173 
SW 
42 

67.0 
64.2 
75.7 
61.2 
36.3 
78.6,  July 
33.2,  Jan. 
45.4 
94,  Sept. 
10,  Jan.  2 
84 
31,  Oct.  1 
64.8 
49.1 
86.4,  July 
26.3,  Jan. 
15.7 
13 

Nov.  13 
April  20 
42.14 
7.66 
16.27 
7.82 
8.11 
7.39,  July 
0.60,  Sept 
2  92,  J  un< 
114 

23,  Aug.  3 

Sept. 
7,  July 
17- 
15.4 

8.2,  Jan. 
5.0,  Jan.  2 
14 

N&  E 
119 
68 
178 
SE 
53 

Mean  Temperature  of  Summer  

Mean  Temperature  of  Winter*  
Highest  Monthly  Mean  

Highest  Absolute  Temperature  

Annual  Mean  Maximum  Temperature  
Annual  Mean  Minimum  Temperature.  ... 
Highest  Mean  Maximum  Temperature  .  . 
Lowest  Mean  Minimum  Temperature..  ... 
Mean  Daily  Range  
Number  of  Times  Maximum  was  above  90°. 
Number  of  Times  Minimum  was  below  32°. 
Date  of  First  Killing  Frost  in  Autumn.  .  .  . 
Date  of  Last  Killing  Frost  in  Spring  

63.1 
47.8 
86.5,  July 
27.0,  March 
15.3 

Annual  Total  Precipitation.  . 

40.61 
12.90 
9.38 
6.32 

Precipitation  for  Spring  

Precipitation  for  Summer  

Precipitation  for  Winter*  

Greatest  Monthly  Total 

5.23,  April 
0.67,  Oct. 
1.29,  Aug.  30 
109 

9.2,  Jan. 
6.0,  Jan.  15 

Least  Monthly  Total  .. 

Greatest  Precipitation  in  24  Hours  
Number  of  Days  with  Rain 

Largest  Number  of  Consecutive  Dry  Days* 
Largest  Number  of  Consecutive  Wet  Days* 
Annual  Snowfall  (unmelted)  
Largest  Monthly  Snowfall  

Largest  Snowfall  in  24  Hours  
Number  of  Days  with  Snow  

Prevailing  Winds  during  Snow  ..  . 

Number  of  Clear  Days  

108 
93 
145 

NW 
31 

Number  of  Partly  Cloudy  Days  . 

Number  of  Cloudy  Days  

Prevailing  Winds  

Number  of  Days  with  Thunderstorms  

*  Three  consecutive  months,  Dec.,  Jan.  and  Feb.,  for  1893,  includes  Dec.,  1892,  Jan.  and  Feb.,  1893,  and  so  c 

MARYLAND   GEOLOGICAL    SURVEY 


185 


[ETEORO LOGICAL,  SUMMARY. 

atitude,  88°  19'  N  :  Longitude,  76°  27'  W ;  Elevation,  20  Feet.    Record  1892  to  1905. 


1808 

1899                   1900 

1901                   1902 

1903 

1904 

1905 

Means. 

57.8 

56.9                   59.1 

56.0                   56.5 

56.0                 i  54.3 

55.9 

56.7 

54.7 

53.4                   53.5 

52.9                   55.2                   56.7 

52.9 

55.5 

54.2 

77.6 

77.6                   79.7 

77.4 

75.3 

73.6 

74.9 

75.7 

76.7 

61.1 

61.5                   65.0 

58.3 

62.0 

58.0 

58.2 

59.7 

60.3 

38.2 

34.0                   38.1 

36.7 

33.3 

37.1 

31.3 

3LO 

35.4 

r9.8,  Aug. 

79.0,  July        82.7.  Aug. 

81.0,  July       78.2,  July 

77.8,  July 

76.6,  July 

77.8,  July 

82.7,  Aug.,  1900 

36.4,  Feb. 

28.9,  Feb.        35.4,  Feb. 

32.2,  Feb.      j  30.4,  Feb. 

34.0,  Dec. 

29.7,  Feb. 

27.8,  Feb. 

26.2,  Jan.,  1893 

13.4 

50.1                  47.3 

48.8                1  47.8 

43.8                  46.9 

50.0 

56.5 

99,  July  2t 

99.  Sept.  6       103,  Aug.  12 

99,  July  2       100,  July  18 

96,  Aug.  26 

96,  July  19 

90,  July  18      103°,Aug.l2,1900 

11,  Feb.  2 

-5.  Feb.  10    9,  Feb.  1 

14,  Dec.  21      14,  Feb.  5t 

8,  Feb.  19 

7,  Feb.  17 

5,  Jan.  31 

-5,  Feb.  10,  1899 

88 

104_                   94 

85                      86 

88 

89 

91 

108 

S2,  May  1 

30,  June  19 

32,  May  14t 

38,  Dec.  15      30,  Apl.  14 

33.  Apl.  29 

34,  Mar.  3 

30,  Apl.  10 

33,  May  9,  1895t 

55.5 

65.1 

67.5 

63.7                  64.4 

63.6 

62.0 

63.8 

64.7     ' 

50.0 

48.7 

50.6 

48.3                  48.6 

48.4 

46.6 

47.9 

48.7 

W.4,  Aug.      |  87.5,  July        91.6,  Aug. 

89.2,  July 

87.0,  July 

86.4,  July 

84.4,  July 

85.4,  July 

91.6,  Aug.,  19CO 

J8.5,  Feb. 

21.8,  Feb.        26.8,  Feb. 

24.8,  Feb.        24.4,  Feb. 

27.5,  Dec. 

22.1,  Feb. 

21.2,  Feb. 

18.5,  Jan.,  1893 

15.5 

16.4                  ie.9 

15.4                  15.8 

15.2 

15.4 

15.9 

16.0 

30 

23                     61 

20                     14 

14 

7 

8 

20 

58 

60 

56 

73 

72 

73 

87 

82 

68 

Nov.  24 

Nov.  13 

Nov.  17 

Nov.  20 

Nov.  23 

Nov.  7 

Nov.  12 

Nov.  5 

Nov.  13 

April  7 

April  4 

April  10 

March  18 

March  27 

April  5 

April  20 

April  19 

April  8 

43.51 

38.38 

38.36 

40.94 

44JO. 

41.10 

29.79 

40.03 

39.05 

12.53 

8.99 

7.61 

10.13 

8.66 

11.18 

6.38 

10.89 

9.84 

14.29 

10.65 

12.74 

14.82 

12.51 

13.65 

10.38 

13.87 

11.75 

9.00 

9.31 

8.96 

6.23 

12.27 

6.56 

5.23 

ilL 

8.14 

7.71 

11.24 

8.14 

6.69 

12.97 

11.12 

6.71 

10.86 

9.32 

7.88.  Aug. 

5.28,  March 

6.77,  Aug. 

7.14,  July 

6.43,  July 

5.56,  July 

4.81,  July       7.71,  July 

7.88,  Aug.,  1898 

1.72,  June 

8.46,  Sept, 
22  23 

0.93,  Nov. 

3.45,  Sept. 
19-20 

1.36,  May        °-37-  Feb- 
5.63,  Aug.  23  2-°°'Jani_13 

2.08,  Aug. 
3.20,  Oct.  5 

1.57,  Nov. 

2.95,  M>ir. 
21-22 

1.13,  Oct. 

2.00,  Sept. 
14  15 

0.40,  Nov.       0.37.  Feb.,  1901 
2.67,  May      j  6.53,  Aug.23,  1900 
14-15 

126_ 

109 

91 

108 

100 

109 

90 

113                   108 

14,  Feb. 

10,  Oct. 

16,  June  18- 

29,  Oct.  15- 

19,  April 

17,  May  5-21 

17,  April 

11,  Nov. 

29days,0ct.,1901 

1-14 
6,  Feb. 

19-28 
6,  Feb.  3-8 

July3 
5,  July 

Nov.  12 
5,  May 

10-28 
5,  Jan.  29- 

5,  Oct.  8-12 

5,  July 

5,  May  14-18 

7,  July,  1897t 

18-22t 

23-27t 

25-29t 

Feb.  2 

22-26 

5.9 

39.9 

17.5 

8.5 

15.4 

7.4 

29.6 

17.0 

17.9 

1.5,  Nov. 

23.0.  Feb. 

9.0.  Feb. 

6.0,  Jan. 

8.1,  Feb. 

3.4,  Jan. 

15.5,  Dec. 

14.0,  Jan. 

23.0,  Feb.,  1899 

0.8,  Nov.  26 

9.0,  Feb.  12 

4.5,  Feb.  17 

3.5,  Jan.  25 

7.5,  Feb.  17 

3.4,  Jan.  24 

8.0,  Dec.  10 

6.2,  Jan.  80 

9.0,  Feb.  12,  1899 

14 

13 

20 

20 

16 

n 

20 

21 

17 

NE&NW 

NE 

NE 

NW 

NW 

NW 

NE&N 

NW 

NW 

120 

124 

116 

103 

112 

85 

96 

93 

108 

6J_ 

75 

96 

99 

123_ 

118 

123 

112 

91 

178 

166 

153 

163 

130 

162 

148 

160 

166 

NW 

NW 

NW&SW 

NW 

NW 

NW 

NW 

NW 

NW 

58 

57 

55 

47 

44 

53 

48 

49 

60 

t  On  other  dates  also. 
13 


186 


THE    CLIMATE   OF    CALVEET    COUNTY 


TABLE  VII. 
HIGHEST  TEMPERATURES  AT  SOLOJIOXS,  MD.,  1892-1905. 


1893.... 
1893. . . . 
1894.... 
1895. . . . 
1893.... 
1897.... 
1898. . . . 
1899. . . . 
1900.... 
1901.... 
1903. . . . 
1903. . . . 
1904.... 
1905.... 


Means . 


00.1 


95      i  84 


81.5     89.4     93.4 


97 

-S 


96.1     94.5     92.1 


72.1     63.3 


Highest. 
Year .... 


•;sth 


88   100 
1896  1895 
17th  9th 


09 

isiir. 


100   J103 
1903  j  1900 
18th  j  12th 


1st 


9th  33d 


103 
1900 
Aug. 


TABLE  VIII. 
LOWEST  TEMPERATURES  AT  SOLOMONS,  MD.,  1892-1905. 


Year. 

1 

•g 
h 

« 
& 

•< 

§j 

1 

Hj 

^ 

13 
>-. 

August. 

I 

1 

> 

o 
fc 

| 

Annual. 

1893  
1893  

10 
4 

10 
16 

19 

18 

32 

32 

47 
47 

57 
59 

61 
61 

63 

62 

54 
46 

40 
36 

23 
24 

16 
21 

10 
4 

1894  

1895 

23 
12 

15 
3 

22 

25 

33 
35 

44 
42 

49 
56 

60 
57 

60 
60 

63 

50 

40 
35 

26 

28 

11 

20 

11 
3 

1896  
1897  
1898  

11 
10 
19 

12 
19 
11 

20 
29 

27 

33 
31 

28 

45 
44 
41 

55 
52 
55 

62 
64 
62 

59 
63 
66 

48 
47 
52 

39 
40 
36 

29 

27 
26 

16 
16 
17 

11 
10 
11 

1899  
1900 

11 
15 

-5 
9 

22 
16 

31 
33 

47 
43 

56 
55 

61 
60 

64 
65 

47 
53 

39 
41 

33 
29 

10 
20 

-5 
9 

1901  
1902  
1903  

17 
18 
15 

18 
14 

8 

15 
20 

28 

34 

28 

47 
46 
41 

56 
55 
52 

66 
60 
60 

66 
58 
61 

52 
51 

47 

40 
38 
37 

25 
32 
20 

14 
20 
13 

14 
14 

8 

1904...  ,  
1905 

9 
5 

7 
6 

26 
20 

30 
34 

47 
46 

54 
56 

62 
64 

60 
61 

43 
51 

35 
39 

28 
28 

13 
23 

7 
5 

Means  

13.8 

10.2 

22.1 

32.1 

44.8 

54.8 

61.4 

62.0 

49.6 

38.2 

26.9 

15.9 

8.2 

Lowest  

4 
1893 

-5 
1899 

15 
1901 

28 
1898 

41 

1898 

49 
1894 

57 
1895 

58 
1903 

43 
1904 

35 

1895 

20 
1903 

10 

1899 

-5 
1899 

Date  

16th 

10th 

6th 

6th* 

9th* 

1st 

31st 

17th 

22d 

30th* 

27th 

31st 

Feb. 
10th 

MARYLAND   GEOLOGICAL    SURVEY 


187 


TABLE  IX. 
MEAN  MAXIMUM  TEMPERATURES  AT  SOLOMONS,  MD. 


Year.                c- 

>"5 

,Q 

£ 

March. 

1 

sA 

03 

5 

® 
c 

3 
<-> 

s*> 

"3 
>-> 

August. 

«1 

1 

| 

>' 

o 
fc 

1 

Annual. 

189°  !  36  0 

44  9 

1893  33.8 
1894....  47  7 

43.8 
44  9 

50.5 
58  0 

63.5 

72.6 

82.4 

86.8 

86.1 

78.7 

69.0 

65.1 

50.3 

64.4 

1895  42.2 
1896  41.7 
1897  40  1 

35.6 
45.1 
43  9 

51.6 

48.2 
54  3 

62.2 
64.2 

71.5 

78.7 

85.1 
83.0 

84.3 

86.7 

90.0 

88.5 

85.1 
79.4 

66.5 
65.8 

56.9 
•?.'.! 

46.9 
46.0 

64.8 
65.7 

1898  44.6 
1899  43  1 

44.4 
36  0 

55.6 
49  7 

60.2 

72.0 

82.9 

86.6 

87.4 

83.5 

69.0 

54.5 

44.8 

65.5 

1900  46.3 
1901  43.9 
1902  40.0 
1903  41.7 
1904  3S.9 

44.1 

36-3 
46.8 
37.3 

49.4 
53.4 
55.7 
57.5 
50.0 

62.7 
58.4 
62.7 
63.3 
59  8 

75.3 
69.9 
74.7 
74.3 

74  0 

84.0 
80.7 
81.0 
74.7 
80  4 

90.2 
89.2 
87.0 
86.4 
84  4 

91.6 
85.9 
83.4 
81.0 

82  6 

84.9 
79.1 
76.8 
77.9 
79  5 

72.9 
68.8 
69.5 
67.1 
65  8 

60.3 
51.3 
61.3 
62  !  3 
53  i 

48.6 
44.2 
44.8 
40.6 
40  5 

67.5 
63.7 
64.4 
63.6 
6°  0 

1905  39.1 

34  5 

54  0 

64  1 

74  5 

81  6 

85  4 

82  9 

•x  i) 

69  1 

55  9 

63  8 

Means  j  41.2 

41.2 

52.6 

62.0 

73.7 

82.1 

86.8 

85.7 

80.2 

68.4 

56.2 

45.5 

64.7 

Highest  Mean  1  47.7 
Lowest  Mean  33.8 
Range  13.9 

46.8 
34.5 
12.3 

58.0 
48.0 
10.0 

64.2 

58.4 
6.8 

78.7 
69.9 
8.8 

85.3 

74.7 
10.6 

90.2 
84.3 
6.9 

91.6 
81.0 
10.6 

85.1 
76.2 
8.9 

72.9 
65.8 
7.1 

62.1 
51.3 
10.8 

50.3 
40.5 
9.8 

67.5 
62.0 
5.6 

TABLE    X. 
MEAN  MINIMUM  TEMPERATURES  AT  SOLOMONS,  MD. 


Year. 

1 

1 

si 

a 

g 

_: 

«<? 

>. 

§ 

"-S 

"3 

1-5 

3° 
< 

*j 

I 

1 

1 

1 

Annual. 

1892  
1893  

27.7 
18.5 
33.8 
27.2 
28.1 
26.3 
32.0 
27.5 
29.6 
30.6 
25.7 
27.6 
23.6 
23.6 

27.2 

29.4 
29.1 
30.5 
19.1 
29.8 
30.9 
28.5 
21.8 
26.8 
24.8 
24.4 
31.0 
22.1 
21.2 

26.4 

27.0 

as.  9 

39.5 
34.8 
32.0 
38.3 
41.3 
34.9 
32.7 
36.6 
36.8 
41.7 
35.2 
36.6 

35.8 

41.0 
46.0 
44.7 
45.7 
47.4 
44.8 
43.3 
44.1 
44.9 
43.8 
44.5 
46.7 
42.4 
45.0 

44.6 

56.6 
54.2 
59.1 
63.8 
60.9 
54.2 
56.1 
56.5 
55.8 
55.5 
56.8 
56.9 
56.2 
58.5 

56.5 

69.6 

65.7 
65.1 
67.0 
65.5 
63.7 
65.1 
67.1 
66.1 
64.8 
63.9 
62.0 
65.2 
65.5 

65.4 

69.7 
69.5 
70.3 
H7.3 
71.1 
70.7 
71.3 
70.5 
72.5 

69  '5 
69.3 
68.9 
70.3 

ToTs 

71.5 

68.7 
67.9 
70.5 
69.5 
68.1 
72.1 
70.3 
73.8 
70.9 
67.1 
68.1 
68-2 
68.5 

69.7 

62.2 
61.6 

£! 

1:1 

65.2 
62.6 
69.1 
63.0 
62.3 
62.3 
63.4 
62.9 

63.8 

49.9 
51.9 
53.2 
46.2 
49.1 
53.4 
54.4 
54.1 
57.7 
60.9 
51.5 
51.3 
49.4 
52.3 

52.0 

39.8 
39.4 
39.2 
42.2 
44.7 
42.4 
40.1 
42.0 
45.2 
36.6 
47.3 
36.8 
38.1 
39.2 

41.2 

29.9 
32.6 
33.3 
33.3 
30.7 
33.9 
31.0 
32.6 
32.9 
29.0 
30.8 
27.5 
26.9 
31.7 

31.1 

47.8 
47.6 
50.3 
47.8 
49.3 
49.1 
50.0 
48.7 
50.6 
48.3 
48.6 
48.4 
46.6 
47.9 

48.7 

1894   
1895 

1896  

1897 

1898  
1899 

1900  

1901  

1902 

1903  

1904  
1905  

Means  

Highest  Mean  
Lowest.  Mean  

33.8 
18.5 
15.3 

31.0 
19.1 
11.9 

41.7 
27.0 
14.7 

47.4 
41.0 
6.4 

60.9     69.6 
53.8  i  62.0 
7.1       7.6 

72.9 
67.3 
6.6 

73.8    69.1 
67.1     61.6 
6.7  j    7.6 

57.7 
46.2 
11.5 

47.3 

36.6 
10.7 

KJSi 

7.0!    ..0 

188  THE    CLIMATE   OF    CALVERT    COUNTY 

Attention  must  be  invited  first  to  some  important  facts  revealed  by  a 
comparison  of  the  record  of  mean  temperatures  for  Solomons  with  the 
normal  temperatures  at  Baltimore  for  88  years,  in  order  that  the  record 
be  not  misinterpreted.  For  convenience  of  comparison  the  mean  tem- 
peratures at  Baltimore  and  Solomons  are  given  below : 

BALTIMORE,  88  YEARS,  1817  TO  1905. 

Jan.    Feb.    Mar.    Apr.    May    June    July    Aug.    Sept.    Oct.    Nov.    Dec.    Year 
34.9     35.8     43.1      54.1     64.0      73.3       77.9     76.1      68.6     56.6     46.6      37.4      55.6 

SOLOMONS,  14  YEARS,  1892  TO  1905. 

Jan.    Feb.    Mar.    Apr.    May    June    July    Aug.    Sept.    Oct.    Nov.    Dec.    Year 
34.2     33.8     44.2      53.3     65.1      73.8      78.6       77.7       72.0      60.2     48.7      38.3      56.7 

A  glance  at  these  records  would  lead  to  the  conclusion  that  Solomons 
is  colder  during  January  and  February  than  Baltimore,  and  that  Febru- 
ary is  a  colder  month  than  January.  As  these  results  are  not  in  con- 
formity with  the  general  relations  of  climate  in  the  region  under  discus- 
sion, some  doubt  might  seem  to  be  thrown  upon  the  accuracy  of  the 
record  for  Solomons.  The  data  for  Solomons  are,  however,  entirely 
reliable,  but  the  conclusions  drawn  from  the  comparison  just  made  are 
incorrect  because  the  period  included  in  the  means  at  the  two  stations  is 
not  the  same.  If  the  comparison  be  made  between  the  means  at  Balti- 
more and  Solomons  for  the  same  period  from  1892  to  1905,  the  follow- 
ing results  are  obtained: 

BALTIMORE,  14  YEARS,  1892  TO  1905. 

Jan.    Feb.    Mar.    Apr.    May    June    July    Aug.    Sept.    Oct.    Nov.    Dec.    Year 
33.2     33.1      43.0      53.0      64.2      72.5       77.2      75.7       68.8      57.3      45.9      35.9      54.8 

Now  it  is  seen  that  Solomons  is  warmer  than  Baltimore  in  about  the 
proper  proportion.  Baltimore  also  shows  a  February  mean  lower  than 
for  January,  an  anomaly  resulting  from  the  fact  that  during  the  past 
decade  temperatures  much  below  the  normal  have  been  experienced  many 
times  in  February,  notably  in  1895,  1899,  1904,  and  1905.  Applying 
the  proper  correction  to  the  short  period  record  for  Solomons,  to  reduce 
it  to  the  equivalent  of  the  Baltimore  period  of  88  years,  the  following 
results  are  found : 5 

5  A  full  explanation  of  the  principal  upon  which  the  correction  is  based 
will  be  found  in  the  report  on  the  climate  of  St.  Mary's  County. 


MARYLAND    GEOLOGICAL    SURVEY 


189 


SOLOMONS,   MEAN  TEMPERATURES,   CORRECTED  TO  88  YEAES. 
Jan.    Feb.    Mar.    Apr.    May    June    July    Aug.    Sept.    Oct.    Nov.    Dec.    Year 
36.9     37.5    44.3       54.4      64.9      74.6      79.3      78.1        71.8      59.5      49.4      39.8      57.5 

If  observations  at  Solomons  be  continued  long  enough  the  mean  tempera- 
tures will  probably  gradually  approach  the  corrected  values  given  above, 


Jan.    Feb.    Mar.    Apr.    May.    Jun.    July.  Aug.    Sep.     Oct.     Nov.    Dec.    Jan 


PIG.  8. — Annual  mean  temperature  curves. —  (a)  for  Solomons,  (b)  for  Wood- 
lawn,   (c)   for  Sunnyside. 

which  show  the  winter  means  higher  than  for  Baltimore,  and  February 
higher  than  for  January,  as  it  should  be.  The  facts  are  given  to  show 
that  serious  errors  may  be  made  by  using  short  period  records  without 


190  THE    CLIMATE   OF    GAL  VERT    COUNTY 

critical  examination.  As,  however,  the  observations  at  Solomons  are 
accurate,  and  truly  represent  the  conditions  prevailing  during  the  period 
which  they  cover,  the  original  data  will  be  used  in  the  further  discussion 
of  the  climate  of  the  place. 

The  annual  mean  temperature  at  Solomons  is  56.7°.  The  fluctua- 
tions in  the  annual  means  have  not  exceeded  5°,  the  warmest  year  of 
record  being  1900,  with  a  mean  of  59.1°  and  the  coldest,  1903,  with  54.3°. 
There  is  necessarily  a  far  greater  variation  in  the  monthly  mean  tem- 
peratures, especially  during  the  season  of  greatest  change,  winter  and 
early  spring,  and  these  variations  afford  a  valuable  method  of  comparing 
climatic  conditions  at  different  stations.  The  coldest  month  at  Solo- 
mons is  February  because,  as  already  stated,  this  month  was  exceptionally 
cold  in  1895  (mean  27.4°),  in  1899  (mean  28.9°),  and  in  1905  (mean 
27.8°),  while  normally  for  this  latitude  January  should  be  the  coldest 
month.  The  coldest  weather  experienced  for  any  length  of  time  at 
Solomons  occurred  during  January,  1893,  the  mean  for  that  month  being 
only  26.2°.  On  the  other  hand  January,  1894,  was  quite  warm,  40.8°, 
and  the  greatest  range  in  monthly  means,  14.6°  is  thus  found  for  the 
mid-winter  month.  The  warmest  month  is  July  with  a  mean  of  78.6°, 
but  it  happens  that  the  highest  summer  mean  temperature  occurred  in 
August,  1900,  when  it  reached  82.7°.  The  fluctuations  in  the  monthly 
means  during  summer  are  much  less  than  in  winter,  as  indicated  by  the 
mean  anomalies  at  the  bottom  of  Table  VI,  which  are  the  averages  of  the 
departures  from  the  normal  from  month  to  month  regardless  of  sign. 

A  brief  comparison  between  the  mean  annual  range  of  temperature 
at  Solomons  and  other  stations  in  Marvland  will  be  of  interest. 


County   
Elevation  feet    .  . 

.  Calvert. 

9() 

Oarrett. 
2500 

Allegany. 
700 

Cecil. 
460 

Record 

1892-1905 

1893  1901 

1865-1875 

Annual  mean  temp  
Highest  monthly  normal  . 
Lowest    monthly   normal  . 

.56.7° 
.78.6°  July. 
.33.8°  Peby. 
44  8° 

46.5° 
67.9°  July. 
23.5°  Feby. 
44  4C 

51.5° 
73.1°  July. 
30.8°  Jany. 

51.9° 
75.8°  July. 
29.8°  Jany. 

Highest  monthly  mean  of 
record     

.  82  7    July 

71  4    July 

77  7    July 

79  4    July 

Lowest  monthly  mean  of 

26  e>°  Jan 

13  5°  Jan 

03  j°  peby 

Range     . 

.56.5° 

57.9° 

55.7° 

56.3° 

MARYLAND    GEOLOGICAL    SURVEY  191 

In  the  interior  of  the  United  States  the  annual  range  in  monthly  mean 
temperatures  (normals)  is  much  greater  at  many  places;  for  instance, 
at  St.  Paul  the  normal  January  temperature  is  11.3°,  July  72.0°,  giving 
a  range  of  60.7°,  as  compared  with  41.8°  at  Solomons,  On  the  other 
hand  it  is  much  smaller  on  the  west  coast  of  Europe,  at  Valencia,,  Ireland, 
only  15.1°  (January  44.4°,  July  59.5°). 

The  mean  temperature  of  spring  at  Solomons  is  54°,  of  summer  77°, 
autumn  60°,  and  winter  35°;  autumn  is  therefore  6°  warmer  than 
spring. 

The  annual  march  of  temperature  at  Solomons  is  shown  graphically 
by  the  upper  curve  in  Figure  8;  for  comparison  the  annual  curves  at 
Sunnyside  and  Woodlawn  are  included.  The  diagram  reveals  readily 
to  the  eye  the  difference  in  temperature  conditions  in  various  portions 
of  the  State. 

Means  of  the  Maximum  and  Minimum  Temperatures. 

In  Tables  IX  and  X  will  be  found  the  means  of  the  maximum  and 
minimum  temperatures.  The  anual  mean  maximum  is  64.7°,  and  the 
mean  minimum  is  48.7°.  The  mean  of  the  maximum  temperatures 
during  a  month  rarely  exceeds  90°,  though  it  has  done  so  twice  at  Solo- 
mons during  the  past  14  years,  on  both  occasions  during  the  extraordi- 
narily warm  summer  of  1900  (July,  1900,  90.2°;  August,  91.6°).  The 
mean  minimum  temperature  is  likewise  rarely  below  20°,  though  this 
has  also  occurred  twice,  namely  in  January,  1893  (18.5°),  and  in  Feb- 
ruary, 1895  (19.1°). 

A  noteworthy  climatic  element  which  should  be  included  in  this 
account  is  expressed  by  the  difference  between  the  normal  mean  maxi- 
mum and  the  normal  mean  minimum  temperatures  for  each  month; 
this  is  called  the  mean  daily  range,  or  the  non-periodic  amplitude. 
Other  important  data  are,  the  differences  between  the  highest  and  lowest 
temperatures  each  month  under  extreme  and  average  conditions,  and 
the  absolute  ranges,  which  give  an  idea  of  the  variability  of  temperature. 
These  data  are  given  in  the  following  table: 


192  THE    CLIMATE   OF    CALVERT    COUNTY 

MEAN  DAILY  RANGE  IN  TEMPERATURE  AT  SOLOMONS. 

Jan.    Feb.    Mar.    Apr.    May    June    July    Aug.    Sept.    Oct.    Nov.    Dec.    Year 
14.0      14.8     16.8      17.4      17.2       16.7       16.5      16.0       16.4      16.4       15.0       14.4      16.0 

Greatest  Daily  Ranges. 
33         33        34         ?4         38         30         27         28         31          31          30         38         38 

Means  of  the  Greatest  Daily  Ranges. 
26.7      26-7     28.8      30.1      29.3      24.8      24.0      23.6      25.5      27.6      24.9      26.8      26.6 

Greatest  Absolute  Range  Each  Month. 
56         65         60          56         58          47          40          39          52          51          51          50          65 

Means  of  the  Greatest  Absolute  Ranges. 
46.4      50.6     50.6      49.4      44.6      38.7       34.1       33.5      42.6      44.9      45.2      45.6          89.9 

Absolute  Range  of  Temperature. 
63         74        67         60          59          50         43         45         56         54         57         55          108 

Extremes  of  Temperature;  Duration  of  Warm  Periods. 
With  respect  to  the  effect  of  temperature  on  vegetation  it  is  to  be 
observed  that  the  mean  values  have  comparatively  little  importance;  the 
vegetative  zones  are  fixed  rather  by  the  extremes  to  which  the  plant  is 
subjected,  and  especially  by  the  lowest  temperature  of  winter.  From  the 
point  of  view  of  man's  personal  comfort  the  maximum  temperatures  of 
summer  are  equally  important,  as  in  large  cities  at  least,  many  deaths 
by  sunstroke  are  recorded  annually.  In  the  open  country  deaths  by 
excessive  heat  are  uncommon  because  there  is  a  freer  movement  of  air 
and  less  humidity.  Tables  VII  and  VIII  give  the  absolute  highest  and 
lowest  temperatures  observed,  and  Table  XI  the  number  of  times  the 
maximum  was  above  90°  and  the  minimum  below  32°.  It  is  a  remark- 
able fact  that  during  the  past  decade  the  highest  and  lowest  temperatures 
recorded  during  a  period  of  more  than  half  a  century  were  experienced. 
The  absolute  extremes  occurred  at  almost  all  stations  in  Maryland  in 
February,  1899,  and  in  August,  1900.  The  maximum  on  record  at 
Solomons  is  103°  on  August  12,  1900.  A  maximum  of  100°  has  occurred 
only  three  times,  once  in  May,  once  in  June,  and  in  August.  The  lowest 
temperature  was  5°  below  zero  on  February  10,  1899.  This  gives  an 
absolute  range  for  Solomons  of  108°,  which  is  less  than  in  other  portions 
of  the  State. 


MARYLAND   GEOLOGICAL    SURVEY 


193 


TABLE  XI. 

NUMBER  OF  TIMES  MAXIMUM  TEMPERATURE  WAS  ABOVE 
AT  SOLOMONS,  MD. 


)",  AND  MINIMUM  BELOW  32" 


Maximum  Temperature  above  90°. 

Minimum  Temperature  below  32°. 

4 

d 

. 

i, 

I 

5 

1 

f 

1 

1 

•< 

IM 

i 

1 

1 

1 

1 

| 
< 

1892.... 

1892.  .     . 

17 

1893.   .. 

0 

7 

4 

0 

15 

1893  

5 

14 

27 

17 

11 

74 

1894.    .. 

0 

10 

2 

2 

18 

1894  

5 

10 

10        16 

5 

46 

1895.  .. 

4 

4 

15 

8 

34 

1895  

12 

23 

26 

8 

71 

1896     .. 

3 

7 

12 

2 

25 

1896..     . 

1 

ITS 

22 

12 

18 

«9 

1897.   .. 

0 

4 

8 

5 

13 

1897.  .     . 

3 

10 

22 

13 

3 

52 

1898.   .. 
1899.   .. 

0 
0 

108 

9 
6 

2 

30 
23 

1898..     . 
1899..     . 

5 
0 

16 
12 

15        17 
19        19 

3 

8 

2 

S 

1900.   .. 

2 

16 

20 

11 

51 

1900..     . 

1 

13 

16 

16 

10 

0 

56 

1901.   .. 

0 

13 

2 

1 

20 

1901..     . 

7 

18 

18 

23 

7 

0 

73 

1903.   .. 

1 

9 

3 

0 

14 

1902..     . 

0 

14 

29 

23 

6 

0 

72 

1903.    .. 

1 

0 

10 

3 

0 

14 

1903..     . 

11 

24 

22 

13 

2 

1 

73 

1904.   .. 

0 

3 

4 

0 

0 

7 

1904..     . 

2 

23 

27 

24 

9 

2 

87 

1905.   .. 

0 

3 

4 

1 

0 

8 

1905.  .     . 

4 

18 

25 

26 

9 

0 

82 

Means... 

1 

3 

8 

6 

3 

20 

Means.. 

4 

15 

21 

19 

8 

1 

68 

On  the  average  the  maximum  temperature  in  Calvert  County  exceeds 
90°  about  20  times  each  year.  In  1900,  however,  90°  was  exceeded  on 
51  days,  while  in  1904  and  1905  this  took  place  only  7  or  8  times.  The 
maximum  exceeds  90°  on  the  average  1  time  in  May,  3  times  in  June, 
8  times  in  July,  6  times  in  August,  and  3  times  in  September. 

The  following  is  a  table  of  dates  on  which  the  maximum  temperature 
was  95°  or  above  at  Solomons: 

1892.— July  26;  August  9. 

1893.— June  20. 

1894.— June  23,  24;  July  12,  13,  14,  28,  29;  August  9;  September  9,  10. 

1895.— May  9,  10,  31;  June  1,  3;  August  10,  11;  September  2,  19,  21,  22,  23. 

1896.— August  5,  7,  9,  10,  11,  12,  13. 

1897— None. 

1898.— June  12,  25,  26;  July  1,  2,  3,  4. 

1899..  .June  6,  8;  September  6,  8. 

1900.— May  15;  July  4,  5,  6,  7,  8,  15,  16,  17,  18,  21;  August  6,  7,  8,  9,  10,  11,  12, 

13,  14,  17,  26,  27;  September  11. 
1901.— July  1,  2,  3,  4,  5,  6,  25,  29,  30. 
1902.— July  5,  18,  20. 
1903.— July  9;  August  25. 
1904.— July  19. 
1905.— July  18,  19. 


194 


THE    CLIMATE   OF    CALVERT    COUNTY 


The  longest  period  of  excessively  warm  weather  certainly  occurred  in 
1900;  in  August  of  that  year  the  maximum  temperature  was  90°  or 
above  on  the  1st,  6th  to  19th  inclusive,  25th  to  29th,  and  on  the  31st, 
or  21  days  in  all.  The  actual  temperatures  during  the  period  from  the 
6th  to  the  14th  of  August  were  as  follows:  6th,  96°;  7th,  100°;  8th, 


\ 


FIG.    9. — Maximum    Temperatures    during   August,    1900. —  (a)    at    Solomons, 
(b)  at  Baltimore,  (c)  at  Deer  Park. 

100°;  9th,  100°;  10th,  101°;  llth,  101°;  12th,  103°;  13th,  95°;  and 
14th,  96°.  July,  1894,  was  probably  the  next  warmest  month,  as  the 
maximum  was  90°  or  above  on  16  days. 

Figure  9  gives  a  graphic  representation  of  the  course  of  the  maximum 
temperatures  during  August,  1900,  at  Solomons,  Baltimore,  and  Deer 
Park.  The  latter  place  has  an  elevation  of  2457  feet  above  sea  level, 
and  here  the  maximum  did  not  reach  90°.  The  curves  sufficiently  indi- 


MARYLAND    GEOLOGICAL   SURVEY  195 

cate,  as  stated  by  Dr.  Fassig  in  his  account  of  the  climate  of  Garrett 
County  (page  264),  that  "the  hot  wave  of  August,  1900,  was  most 
intense  near  the  earth's  surface  below  the  mountain  tops."  During  the 
period  of  most  intense  heat  the  winds  at  Solomons  were  light  north- 
westerly, 6th  to  12th,  and  when  a  shift  to  south  and  southeast  took  place, 
there  was  an  immediate  decline  in  temperature. 

Frequency  and  Duration  of  Cold  Periods. 

The  minimum  temperature  falls  below  the  freezing  point  on  the  aver- 
age 68  times  a  year.  In  the  cold  year,  1904,  the  minimum  was  below  32° 
87  times,  while  in  1894  it  was  below  freezing  only  46  times.  Freezing 
temperatures  occur  on  the  average  4  times  in  November,  15  times  in 
December,  21  times  in  January,  19  times  in  February,  8  times  in  March, 
and  1  time  in  April.  Of  course  these  figures  indicate  a  far  less  fre- 
quency of  freezing  temperatures  in  Calvert  County  than  in  the  moun- 
tainous section  of  the  State.  In  Garrett  County  freezing  weather  occurs 
at  one  time  or  another  in  every  month  of  the  year,  and  the  average  num- 
ber of  days  with  a  minimum  of  32°  or  less  for  that  county  is  160;  here 
the  frequency  has  varied  from  a  minimum  of  140  times  at  Grantsville 
in  1897  to  a  maximum  of  187  times  at  Deer  Park  in  1895. 

The  following  table  gives  the  dates  on  which  the  temperature  fell  to 
20°  or  below  at  Solomons: 

1892.— January  4,  16,  17,  23,  27;  February  6,  13,  17,  18;  December  25. 

1893.— January  10,  11,  13,  14,  15,  16,  17,  18,  21,  22;  February  5,  20,  21;  March  5. 

1894.— February  5,  24,  25;  December  29,  30. 

1895.— January  1,  2,  5,  13,  14,  25;  February  1,  3,  4,  5,  6,  7,  8,  9,  10,  11,  12,  13,  14, 

15,  17,  18,  23;  December  14. 

1896.— January  4,  5,  6,  7;  February  17,  18,  20,  21,  22;  March  14;  December  24, 

25,  28. 

1897.— January  25,  26,  27,  28,  29,  30,  31;  February  1;  December  24,  25. 
1898. — January  2;  February  1,  2,  3,  4;  December  14,  15. 
1899.— January  1,  2,  11,  29;    February  1,  2,  8,  9,  10,  11,  12,  13,   14,  15,  16; 

December  27,  28,  29,  30,  31. 
1900.— January  1,  2,  3,  4,  27,  29,  30,  31;   February  1,  2,  18,  19,  20,  25,  26,  27; 

March  12,  18;    December  15,  17. 
1901. — January  19,  20;  February  1,  6,  7,  13,  14,  23,  24;  March  6,  7;  December  6, 

16,  17,  18,  19,  20,  21,  22. 


196 


THE    CLIMATE   OF    CALVERT    COUNTY 


1902.— January  4,  5,  6,  29;  February  3,  4,  5,  6,  8,  9,  10,  11,  12,  13  14,  19,  20; 

March  19;  December  27. 
1903.— January  9,  10,  12,  13,  19,  20;  February  17,  18,  19,  20;  November  27; 

December  26,  27. 
1904.— January  3,  4,  5,  6,  18,  19,  20,  27,  28,  30;  February  1,  2,  3,  4,  10,  12,  13, 

16,  17,  18,  20,  21,  26;  December  10,  11,  12,  13,  14,  15. 
1905.— January  4,  5,  14,  15,  16,  25,  26,  27,  29,  31;  February  2,  3,  4,  5,  8,  11,  13, 

14,  15, 16,  17,  19;  March  2;  December  none. 


FIG.  10. — Minimum  Temperatures  during  February,  1899. — (a)   at  Solomons, 
(b)  at  Sunnyside. 

The  longest  consecutive  period  of  temperatures  below  20°  was  from 
February  3  to  15,  1895;  during  that  month  the  minimum  was  at  the 
freezing  point  or  below  for  25  days.  The  detailed  record  for  this  period 
is  as  follows :  3d,  15°  ;  4th,  19°  ;  5th,  12°  ;  6th,  6°  ;  7th,  10°  ;  8th,  3°  ; 
9th,  7°;  10th,  14°;  llth,  12°;  12th,  15°;  13th,  18°;  14th,  13°;  15th, 
15°. 


MARYLAND    GEOLOGICAL    SURVEY  197 

During  the  most  severe  winters  the  Patuxent  Eiver  is  frozen  over  occa- 
sionally as  far  down  as  its  mouth,  thus  blocking  navigation.  In  Jan- 
uary, 1893,  Dr.  Marsh  stated :  "  On  the  night  of  the  10th  the  Patuxent 
Eiver  froze  over  at  its  mouth  for  the  first  time  in  12  years,  and  it  con- 
tinued frozen  until  January  30."  In  February,  1895,  the  river  was 
frozen  over  down  to  its  mouth,  remaining  closed  until  the  24th.  Similar 
facts  were  noted  in  February,  1899,  and  in  January,  1905. 

During  the  cold  wave  of  February,  1899,  the  minimum  was  below  20° 
at  Solomons  for  9  consecutive  days  (9th  to  16th),  and  this  is  the  only 
period  during  which  temperatures  below  zero  were  ever  recorded  at  the 
station,  viz.,  February  10,  5°  below  zero;  llth,  3°  below  zero.  The 
record  at  Solomons  from  February  9  to  16,  1899,  in  comparison  with 
Sunnyside,  Garrett  County,  is  shown  in  Figure  10. 

The  Advent  of  Spring. 

The  date  of  the  advent  of  spring  for  Calvert  County  is  given  as  March 
21,  by  Mr.  F.  J.  Walz,  in  his  report  on  the  Meteorology  and  Climatology 
of  Maryland  (Vol.  I,  page  487).  This  was  based  on  the  fact  that  about 
this  time  the  daily  mean  temperature  remains  permanently  above  44°. 
From  the  point  of  view  of  agricultural  interests,  the  dates  of  the  last 
killing  frost  in  spring,  and  the  first  killing  frost  in  autumn  are  of 
much  practical  importance,  and  often  exert  a  marked  influence  on  the 
yield  of  crops.  As  a  killing  frost  is  defined  as  one  which  will  cause  the 
death  of  relatively  hardy  vegetation,  including  nearly  all  the  plants  of 
ordinary  cultivation,  the  average  date  of  the  last  killing  frost  in  spring 
seems  to  afford  a  better  criterion  of  the  advent  of  spring  than  the  arbi- 
trarily assumed  mean  temperature  of  44 °.6  At  Solomons  this  date  is 
April  8.  The  average  date  of  the  first  killing  frost  in  autumn  is 
November  13,  so  that  the  duration  of  the  growing  season  is  on  the  aver- 
age 219  days.  The  length  of  the  crop  season  does  not  fluctuate  very 
much  on  account  of  proximity  to  the  waters  of  the  Chesapeake.  The 

8  U.  S.  Weather  Bulletin  No.  31,  p.  69. 


198  THE    CLIMATE   OF    CALVERT    COUNTY 

dates  of  the  first  and  last  killing  frosts  at  Solomons  from  1893  to  1905 
are  given  in  Table  XII.  The  latest  date  with  a  minimum  tempera- 
ture of  32°  was  April  27,  1893,  but  a  light  frost  has  occurred  as  late  as 
May  26  (1899).  The  earliest  date  of  the  last  killing  frost  in  spring 
was  March  18,  1901.  The  earliest  first  light  frost  in  fall  occurred  Oc- 
tober 2,  1899,  and  in  1898  the  date  of  the  first  killing  was  deferred  to 
November  24. 


TABLE  XII. 

DATES  OP  FIKST  AND  LAST  KILLING  F"ROST  AT  SOLOMONS,  MD. 

Year.  First  in  Autumn.  Last  in  Spring. 

1893  November     1.  April     27. 

1894  November  12.  March   28. 

1895  November     3.  March   29. 

1896  November  14.  April        9. 

1897  November  13.  April     20. 

1898  November  24.  April        7. 

1899  November  13.  April        4. 

1900  November  17.  April      10. 

1901  November  20.  March    18. 

1902  November  23.  March   27. 

1903  November     7.  April        5. 

1904  November  12.  April     20. 

1905  November     5.  April      19. 
Average.  November  13.  April        8. 


PRECIPITATION. 

As  the  amount  of  rainfall  determines  the  agricultural  productiveness 
of  a  country,  precipitation,  which  includes  melted  snow,  sleet,  and  hail, 
is  the  most  important  element  of  climate  after  temperature,  but  it  is 
far  more  variable.  For  climatological  purposes  the  following  data  are 
required :  1,  the  monthly  and  annual  rainfall ;  2,  the  maximum  amount 
of  rain  during  a  short  period  of  time,  as  a  day  or  an  hour ;  3,  the  number 
of  rainy  days,  and  duration  of  consecutive  days  with  rain;  and  4,  the 
periods  of  drought  or  longest  consecutive  number  of  dry  days.  Table 
XIII  gives  the  monthly  and  annual  precipitation  at  Solomons;  and 
Table  XIV  the  greatest  precipitation  in  24  hours. 


MARYLAND   GEOLOGICAL    SURVEY 


199 


TABLE  XIII. 
MONTHLY  AND  ANNUAL  PRECIPITATION  AT  SOLOMONS,  1892  TO  1905. 


Percentage  of  annual  mean. 


TABLE  XIV. 
GREATEST  PRECIPITATION  IN  24  HOURS  AT  SOLOMONS,  MD. 


ts 

i 

Year. 

,0 

2 

~ 

£ 

J 

>, 

|3 
SO 

4J 

^ 

> 

0 

P 

a 

k 

i 

3 

a 

1-5 

«j 

I 

$ 

Z 

0 

3 

1892  

1.00 

1.4 

1.18 

1.26 

1.09 

0.91 

1.29 

0.43 

0.56 

1.04 

1.13 

1.29 

1893  

0.67 

1.67 

1.06 

1.48 

1.05  !  1.72 

1.08 

1.47 

0.83  1  2.15 

2.50 

0.88    2.50 

1894 

0  88 

1  05    o  ;w 

1  59 

2.37    0.45 

0.63 

0  52     1  12     2.32 

0.99 

1.58     2.37 

1895  

0.80 

0.56 

1.13 

1.85 

1.00    2.00 

1.16 

1.05  '  0.42     1.18 

0.84 

0.71     2.00 

1896  
1897 

0.95 
0  83 

3.75  1  6.65 
1  93    0  82 

0.69 
1  14 

1.35    1.10 
0.55    %  99 

1-10 
1  33 

0.95     1.50     0.55 
1  03    0  50     1.42 

0.85 
0.73 

0.84    3.75 
1.11     2.92 

1898  

0.70 

1.28     1.10 

0.88 

1.24 

1.12 

1.80 

2.37  i  2.46     0.82 

0.81 

0.67     2.46 

1899 

0  62 

0  87 

1  19 

0  67 

0.56    n.sn 

1.40 

0  79     3  45     2.00 

0.36 

0.45    3.45 

1900  

1.35 

0.77 

0.80 

1.80 

0.65 

2.05 

1.10 

5.53    0.88     2.21 

1.07 

1.52     5.53 

1901  

2.00 

0.13 

0.77 

1.30 

0.95     1.23 

1.43 

1.11     1.31     1.21 

1.57 

1.45    2.00 

1902  

1.20 

1.62 

0.98 

1.73 

1.19     1.46 

3.60 

0.72     1.35     3.20 

1.22 

069    3.20 

1903 

1  24 

1  60 

2.95 

0.70 

1.04     1.50 

1.78 

0.95     0.58     0.89 

1.05 

0.62    2.95 

1904  

0.52 

0.76 

0.46 

0.50 

1.00     1.10 

1.36 

1.52 

2.00    0.85 

1.45 

1.10    2.00 

1905  

0.77 

1.13 

0.60 

0.80 

2.67 

1.67 

2.24 

0.97 

1.15     0.50 

0.20 

1.26 

2.67 

Greatest  

2.00 

3.75 

2.95 

1.85 

2.67     2.92 

3.60 

5.53    3.45 

3.20 

2.50 

1.58 

5.53 

Year 

1901 

1896 

1903 

1895 

1905     1897 

1902 

1900     1899 

1902 

1893 

1894 

1900 

Date  

11-12 

5-6 

21-22 

8 

14-15J    24 

30 

23    j  19-20 

6 

3 

26-27 

Asr 

The  annual  average  precipitation  is  39.05  inches,  which  is  slightly  less 
than  the  average  for  Calvert  County.  The  largest  amount  falls  in  July, 
average  4.83  inches,  which  is  12  per  cent  of  the  annual  amount,  and 


200 


THE    CLIMATE   OF    CALVERT    COUNTY 


the  least  falls  in  November,  average  2.41  inches,  which  is  6  per  cent  of 
the  annual.  The  distribution  is  seen  to  be  quite  uniform  in  character. 
During  the  past  14  years  Solomons  has  not  received  a  monthly  total  of 
as  much  as  10  inches;  the  greatest  amount  was  7.88  inches  in  August, 
1898.  On  the  other  hand  amounts  of  less  than  1.00  inch  are  of  occa- 
sional occurrence,  as  in  February,  1901,  monthly  total  0.37  inch,  Septem- 
ber, 1895  (0.76  inch),  September,  1897  (0.50  inch),  October,  1892  (0.67 
inch),  November,  1899  (0.93  inch),  November,  1905  (0.40  inch)  and 
December,  1896  (0.92  inch).  The  possible  range  is  from  7.88  inches  to 
0.37  inch.  The  driest  year  was  1894. 


M     A     M      J 


A      8       O      N      D 


FIG.  11. — Precipitation  for  each  month  in  the  year  at  Solomons. —  (a)  greatest, 
(b)  average,  (c)  least. 

Calvert  County  does  not  rank  very  high  as  regards  excessive  rainfalls 
during  brief  intervals  of  time,  as  shown  by  the  footings  of  Table  XIV. 
The  amount  usually  considered  an  excessive  rate  in  24  hours  is  2.50 
inches,  in  1  hour  1.00  inch.  It  appears  from  the  table  that  the  excessive 
rate  (2.50  inches  in  24  hours)  has  occurred  in  the  following  months: 
February,  1896  (3.75  inches),  March,  1903  (2.95  inches),  May,  1905 
(2.67  inches),  June,  1897  (2.92  inches),  July,  1902  (3.60  inches), 
August,  1900  (5.53  inches),  September,  1899  (3.45  inches),  October, 
1902  (3.20  inches),  and  November,  1893  (2.50  inches).  The  heaviest 
rainfall  in  24  hours  was  5.53  inches  August  23,  1900. 


MARYLAND   GEOLOGICAL    SURVEY  201 

The  following  table  gives  the  heaviest  rains  for  briefer  periods : 

1892. — June  23,  0.93  inch  in  15  minutes  ;  30,  0.45  in  16  minutes. 
1895. — June  30,  1.15  inches  in  30  minutes. 
1897.— June  24,  2.92  inches  in  2  hours  and  15  minutes. 
1900.— August  23,  5.00  inches  in  4  hours  and  45  minutes. 
1901. — June  7,  0.90  inch  in  20  minutes. 

July  19,  1.40  inches  in  45  minutes;  25,  1.00  in  1  hour. 

August  12,  0.75  inch  in  30  minutes. 
1903.— May  29,  0.90  inch  in  30  minutes. 

June  8,  0.44  inch  in  18  minutes. 

July  11,  0.75  inch  in  25  minutes. 
1905. — May  14,  1.30  inches  in  30  minutes. 

June  21,  0.63  inches  in  13  minutes. 

August  13,  0.75  inch  in  30  minutes. 

Duration  of  Dry  and  Wei  Periods. 

The  distribution  of  rainfall  in  Maryland  is  so  uniform  that  droughts 
are  never  of  long  enough  duration  to  cause  an  entire  failure  of  crops, 
though  they  have  frequently  been  long  enough  to  materially  reduce  the 
yield,  and  to  cause  the  failing  of  wells  in  country  districts.  Long  periods 
of  fair  weather  are  usually  considered  a  favorable  climatic  feature,  at 
least  they  are  agreeable  to  people  whose  occupation  is  not  farming  until 
the  dust  becomes  objectionable.  Periods  of  dry  and  wet  weather  are 
climatic  elements  of  much  interest.  Below  are  given  the  dates  of  all 
periods  during  which  no  appreciable  precipitation  'fell  at  Solomons  for 
10  or  more  consecutive  days,  and  also  the  rainy  periods  of  5  days  or 
more,  with  the  total  rainfall  during  each: 

Dry  Periods.  Wet  Periods. 

1893.— March  25  to  April  6  (13  days).      1893.— Feb.  9,  10,  11,  12,  13  (2.69). 

December  17  to  27   (11). 
1894.— Feb.  27  to  March  12  (13).  1894.— May  16,  17,  18,  19,  20  (2.64). 

Aug.  28  to  Sept.  7  (11).  . 

Oct.  14  to  23  (10). 

Dec.  13  to  24  (12). 
1895.— Feb.  17  to  27  (11).  1895.— April  27,  28,  29,  30;   May  1,  2, 

July  31  to  Aug.  11  (12).  3   (3.88). 

Sept.  7  to  18   (12). 

Sept.  26  to  Oct.  7  (12). 

Oct.  14  to  30  (17). 
14 


202 


THE    CLIMATE   OF    CALVERT    COUNTY 


1896.— May    18,    19,    20,    21,    22,    23 

(1.76). 
July  6,  7,  8,  9,  10   (2.41). 


1896.— Jan.  1  to  16  (17). 

March  1  to  10  (10). 

Sept.  30  to  Oct.  10   (11). 

Oct.  24  to  Nov.  13  (11). 

Dec.  1  to  14  (14). 
1897.— Dec.  23,  '96  to  Jan.  12  (21). 

March  25  to  April  3  (10). 

Aug.  31  to  Sept.  22  (23). 

Nov.  15  to  25  (11). 
1898.— Feb.  1  to  14  (14). 

March  5  to  14  (10). 

May  31  to  June  10   (11). 
1899.— Oct.  19  to  28  (10). 
1900.— April  23  to  May  2  (10). 

June  18  to  July  3  (16). 

Aug.  30  to  Sept  10  (12). 

Oct.  14  to  23  (10). 

Nov.  10  to  24  (15). 
1901.— Dec.  31  '00  to  Jan.  9  (10). 

Feb.  10  to  21  (12). 

April  26  to  May  7  (12). 

Oct.  15  to  Nov.  12   (29). 
1902.— Jan.  4  to  17  (14). 

Feb.  3  to  15  (13). 

March  18  to  27  (10). 

April  10  to  28   (19). 

May  28  to  June  6  (10). 

July  7  to  17   (11). 

Aug.  23  to  Sept  1  (10). 

Sept  10  to  19  (10). 

Oct.  13  to  26  (14). 

Nov.  7  to  17  (11). 
1903.— March  10  to  20  (11). 

May  5  to  21  (17). 

Oct.  25  toNov  4  (11). 

Nov.  18  to  28  (11). 
1904.— April  9  to  25  (17). 

Aug.  29  to  Sept.  13  (16). 

Sept.  21  to  Oct.  5  (15). 
1905.— April  14  to  25  (12). 

May  17  to  28  (10). 

Sept.  21  to  Nov.  1  (11). 

The  longest  period  of  drought  on  record  was  from  October  15  to 
November  12,  1901,  or  29  consecutive  days  without  more  than  a  trace 
of  rain.  This  late  fall  drought  was  probably  not  as  injurious  to  crops 
.as  the  earlier  one  of  23  days'  duration  from  August  31  to  September  22. 


1897.— July  17,  18,  19,  20,  21,  22,  23, 

(3.63). 
Oct.  22,  23,  24,  25,  26,  27  (3.57).. 

1898.— Feb.  18,  19,  20,  21,  22  (1.71). 

Aug.  8,  9,  10,  11,  12   (5.86). 

Dec.  19,  20,  21,  22,  23  (1.39). 
1899.— Feb.  3,  4,  5,  6,  7,  8  (1.88). 
1900.— July  23,  24,  25,  26,  27   (1.97). 

Aug.  20,  21,  22,  23,  24  (5.75). 


1901.— May  25,  26,  27,  28,  29   (1.29). 
Dec.  26,27,28,29,  30  (2.33). 


1902.— Jan.    29,    30,    31;     Feb.    1, 
(1.56). 


1903.— Oct.  8,  9,  10,  11,  12  (1.85). 


1904.— July  22,  23,  24,  25,  26  (2.50). 


1905.— May  14,  15,  16,  17,  18  (4.28). 


MARYLAND   GEOLOGICAL   SURVEY  203 

.1897.  It  appears  from  the  table  that  droughts  of  10  days'  duration  or 
more  have  occurred  at  Solomons  53  times  in  the  last  13  years. 

During  the  same  time  the  number  of  times  rain  has  fallen  on  5  or 
more  consecutive  days  was  only  19.  Rain  on  4  days  or  more  occurred 
25  times.  These  exclude  traces  not  considered  as  rain.  The  longest 
duration  of  rainy  days  is  7,  viz.,  April  27  to  May  3,  1895,  during  which 
time  3.88  inches  fell,  and  July  17  to  23,  1897,  with  3.63  inches.  The 
heaviest  rainfall  during  any  of  the  rainy  periods  above  recorded  was 
5.86  inches  from  August  8  to  12,  1898. 

The  average  number  of  days  on  which  0.01  inch  or  more  of  rain  falls 
at  Solomons  is  108.  July  has  the  largest  number  of  rainy  days  (12), 
September  the  least  (6).  The  probability  of  rain  in  summer  is  0.4; 
in  late  winter  and  spring  0.3,  and  in  autumn  only  0.2. 

When  rain  occurs  the  average  amount  received  each  rainy  day  (or  the 
intensity  of  rainfall)  is  as  follows : 

INTENSITY  OF  RAINFALL  AT  SOLOMONS. 

Jan.    Feb    Mar.    Apr.    May    June    July    Aug.    Sept.    Oct.    Nov.    Dec. 
0.28     0.3S     0.33      0.35     0.34      0.36      0.40      0.41       0.44      0.44      0.30     0.36 

Snowfall  (Unmelted). 

The  heaviest  snow  storms  in  southern  Maryland  are  invariably  asso- 
ciated with  the  Gulf  type  of  barometric  depressions,  which  move  north- 
eastward from  the  Gulf  of  Mexico  over  the  Atlantic  States  or  along  the 
coast  line;  light  snow  also  frequently  falls  after  the  passage  of  other 
depressions  over  or  near  the  boundaries  of  the  State,  but  only  after  the 
shift  of  the  wind  to  west  or  northwest.  This  statement  is  borne  out  by 
the  direction  of  the  prevailing  winds  during  snow  storms  in  Calvert 
County,  which  is  frequently  northeast  or  north  to  northwest,  but  very 
rarely  frofn  any  southerly  and  easterly  direction.  The  annual  snowfall 
(unmelted)  at  Solomons  is  presented  in  Table  XV. 

The  annual  total  is  about  18  inches.  As  several  winters  have  recently 
been  very  severe,  this  amount  is  probably  above  the  true  normal  for  this 
region.  Small  amounts  of  snow  may  fall  in  April  and  November,  usu- 
ally less  than  an  inch,  while  the  largest  averages  occur  in  January  and 
February,  6  inches.  Snow  falls  on  the  average  on  17  days  each  year. 


204 


THE    CLIMATE   OF    CALVERT    COUNTY 


The  largest  snowfall  in  any  year  was  40  inches  in  1899,  and  the  least 
5  inches  in  1896.  The  most  remarkable  fall  of  snow  in  Calvert  County 
took  place  during  the  noted  cold  wave  of  February,  1899.  In  that 
month  23  inches  was  recorded  at  Solomons.  The  largest  snowfall  in  24 
hours  was  9  inches  on  February  12,  1899;  next  to  this  is  8  inches  Decem- 
ber 10,  1904;  7.5  inches  December  5,  1893,  and  February  17,  1902. 
Snow  does  not  usually  remain  unmelted  on  the  ground  for  any  length  of 
time  in  southern  Maryland,  and  therefore  the  following  record  of  un- 
melted snow  on  the  ground  at  Solomons  during  February,  1899,  is 
unique : 

February  1,  4  inches;  2d,  2  inches;  3d,  1  inch;  5th,  0.5  inch;  6th,  3.5 
inches;  7th,  6.0  inches;  8th,  5.5  inches;  9th,  5.5  inches;  10th,  5.0  inches; 
llth,  5.0  inches;  12th,  12.0  inches;  13th,  20.0  inches;  14th,  16.0  inches; 
15th,  12.0  inches;  16th,  12.0  inches;  17th,  10.0  inches;  18th,  6.0  inches; 
19th,  3.0  inches;  20th,  1.0  inch. 

TABLE  XV. 

MONTHLY  AND   ANNUAL   SNOWFALL    (UNMELTED)    AT   SOLOMONS,   MD. 


•g 

_: 

« 

1 

s 

I 

1 

A 

<5 

& 

2 

3 
1-5 

3 

*-} 

< 

tt 

s 

& 

1 

e 
< 

1892 

9  2 

3  5 

1893  

1  3 

4  8 

6  8 

o 

o 

o 

o 

Q 

Q 

o 

0  1 

7  *> 

26  5 

1894           .     .  . 

1  5 

8  8 

T 

T 

o 

0 

o 

Q 

Q 

Q 

Q 

2  8 

13  1 

1895  

16  0 

11.8 

1  o 

o 

o 

o 

o 

o 

o 

o 

T 

2  7 

31  5 

1896  

T 

0  2 

1  0 

o 

Q 

Q 

Q 

Q 

Q 

2  0 

1  7 

4  9 

1897 

8  2 

6  0 

o 

O 

o 

« 

Q 

o 

Q 

Q 

1  2 

1898  
1899  

1.0 

7  7 

0.4 
23  0 

0 
6  0 

2.0 

o 

0 

Q 

§ 

§ 

0 

Q 

0 

o 

0 

Q 

1.6 

o 

1.0 
3  9 

5.9 
39  9 

1900  

1.0 

9  0 

5  0 

T 

o 

o 

o 

Q 

o 

o 

T 

2  5 

17  5 

1901  

6  0 

0  7 

1  0 

T 

Q 

o 

Q 

Q 

o 

o 

0  2 

0  6 

8  5 

1903  

6.1 

8.1 

T 

o 

o 

o 

o 

o 

o 

o 

15  4 

1903  
1904 

3.4 
6  5 

1.0 

5  8 

0 

0  8 

0 

o 

0 

Q 

0 

Q 

0 

Q 

0 

Q 

0 

o 

0 

1.0 
1  0 

2-0 

7.4 
99  (5 

1905  

14.0 

2.3 

0.2 

T 

0 

0 

0 

0 

0 

0 

T 

0.5 

17.0 

Means  

6.3 

6.1 

1.7 

0  *> 

o 

o 

o 

o 

o 

o 

0.4 

3  2 

17  9 

• 

Greatest  Amount. 

V 

23.0 
0  2 

6.8 

o 

2.0 

Q 

2.0 

Q 

15.5 
0  6 

39  9 
4  9 

T  Indicates  traces  of  precipitation. 

WINDS  AND  WEATHER. 

From  the  description  of  the  station  at  Solomons  it  will  be  seen  that 
the  local  topography  is  such  as  to  permit  free  wind  movement;  how  far 


MARYLAND    GEOLOGICAL    SURVEY 


205 


the  position  of  forests  north  and  south  of  the  station,  and  the  inclina- 
tion of  the  land  surface  upward  towards  the  northwest  may  influence 
the  prevailing  winds  is  not  known.  The  direction  of  the  wind  from 
October  to  March  is  generally  northwest;  that  the  prevailing  winds  are 
southeast  during  April,  May,  and  June  may  be  a  local  phenomenon,  due 
to  the  rapid  heating  of  the  soil  in  the  interior,  and  the  inflow  of  cooler 
air  from  the  surface  of  the  Bay.  The  winds  then  shift  to  southwest. 
There  are  no  records  of  wind  velocities,  but  the  observer  has  frequently 
mentioned  the  dates  of  severe  wind  storms  and  high  tides,  such  as 
occurred,  for  instance,  on  October  13,  1893;  February  6,  1896;  extremely 
high  tides  October  22  to  28,  1897;  storms  October  18,  1898;  September 
14,  1904,  etc. 

On  the  average  there  will  be  50  thunderstorms  each  year  at  Solomons ; 
the  largest  number  is  recorded  in  July  and  June;  while  thunderstorms 
are  uncommon  in  winter  they  have  occurred  in  every  month  of  the  year. 

TABLE   XVI. 
PREVAILING  WINDS  AT  SOLOMONS,  MD. 


Year 

1 

I 

A 

i 

A 

< 

£ 

a 

p 

3 
1-5 

j*> 
"3 

Hj 

bib 

3 
<J 

I 

1 

K 

1 

Annual 

1893 

NW 

NE 

NW 

NW 

SE 

sw 

SW 

SE 

SE 

NW 

NW 

N 

NW 

1893 

NW 

NW 

SE 

SE 

SE 

SW 

SW 

SE 

SE 

SE 

NW 

SW 

SE 

1894  
1895      

NW* 

sw 

NW 

NW 

NW 
NW 

SE 
SE 

SE 
SW 

SE 
SE 

SW 
NW 

SE 
SE 

SE 
SE 

NW 
NW 

NW 

N 

NW 
NW 

NW* 
NW* 

1896  
1897 

N 
NW 

SW 

NW 

NW 

SE 

SE 
SE 

SE 
SE 

SE 
SE 

SW 

SE 

SW 
SE 

SE 
SE 

NW* 

NE 

SW* 
NW 

NW 
NW 

SW 

SE 

1898 

NW 

NW 

SE 

NW 

SE 

SE 

E 

SW 

NE 

NW 

NW 

SW 

NW 

1899 

g 

NW 

NW 

SE 

SE 

SW* 

SE 

NE 

SE 

E 

NW 

N\V 

NW 

]900  

SW 

NW 

NW 

NW 

SE 

SW 

SW 

E 

E 

NE 

SW 

NW 

SW* 

1901  
1903  
1903  

NW 
NW 

NW 

NW 
NW 
NW 

SW* 
NW 
NE 

SE 
NW 
NW 

NW 
SE 
SE 

SE 
SE 
SE 

SW 
SW 

SW 

SW 
SW 

SE 

SW 

S 
SE 

NW 
NW 
NW 

NW 
NW 
NW 

NW 
NW 
NW 

NW 
NW 
NW 

1904 

NW 

NW 

NW 

SE 

SE 

SE 

SW 

SW 

SW 

NW 

NW 

NW 

NW 

1905  

NW 

NW 

SW 

SW 

SE 

SW 

NW 

SW 

SE 

NW 

NW 

NW 

NW 

Means  

NW 

NW 

NW 

SE 

SE 

SE 

SW 

SW* 

SE 

NW 

NW 

NW 

NW 

Other  directions  also. 


206 


THE    CLIMATE    OF    CALVERT    COUNTY 


The  prevailing  character  of  the  weather  is  indicated  by  Table  XVII. 
The  average  number  of  clear  days  is  greatest  during  August,  September, 
and  October,  and  least  during  early  spring.  The  annual  number  of 
cloudy  days  is  166;  this  is  somewhat  high,  and  it  is  thought  to  include 
many  days  on  which  rain  fell,  but  which  under  stricter  application  of  the 
rules  for  determining  the  character  of  the  day  would  have  been  recorded 
partly  cloudy.  The  average  number  of  days  with  fog  is  9,  with  sleet 
and  hail  6. 

TABLE  XVII. 

CHARACTER  OF  WEATHER  AT  SOLOMONS,  MD. 


,c5 

IS 

f 

Number  of  Days 

a 
a 

1-5 

t 

1 
1 

B 

•£ 

K 

* 

a 

S 

>-5 

jj 
'a 

1-5 

$ 
^ 

I 

+3 

1 

1 

1 

a 
a 
.<j 

Clear.    .. 

7 

8 

_ 

7 

g 

9 

9 

10 

12 

13 

9 

9 

Ills 

Partly  cloudy  
Cloudy  

7 

6 
14 

7 
17 

8 
15 

8 
15 

8 
13 

8 
14 

9 
12 

8 
10 

7 
11 

7 
14 

8 
14 

1(1 

1  nii 

Rainy  
With  snow  

10 
5 

10 
5 

10 
2 

9 

10 
0 

9 
0 

12 

0 

9 
0 

6 
0 

7 
0 

8 

1 

8 
3 

ins 
17 

With  thunderstorms 

0 

1 

3 

4 

8 

9 

11 

1 

4 

2 

1 

0 

50 

For  the  sake  of  completing  the  records  for  Calvert  County,  the  tempera- 
ture and  precipitation  data  at  Prince  Frederick  are  given  in  Table 
XVIII. 

TABLE  XVIII. 

MONTHLY  MEAN  TEMPERATURES  AND  TOTAL  PRECIPITATION  AT  PRINCE  FREDERICK,  MD. 
Record  by  Alfred  Presson. 


Monthly  Mean  Temperatures. 


Monthly  Total  Precipitation. 


Fear 

a* 

1 

a 

8 

A 
4 

h 

08 

£ 

a> 

a 

3 
-) 

Year 

A 

a 

HS 

I 

A 
d 

I 

| 

r-5 

1899 

28  8 

43  0 

54  3 

64  7 

73  6 

1899 

1900  

40  6 

64  2 

73  0 

1900 

2  20 

3  65 

1  19 

6  1° 

1901  
1909 

35.6 

30.4 

45.4 

60.0 

63.1 

72.0 

1901  

2.99 

0.47 

383 

6.47 

2.85 

2.00 

1903    

33.8 

38  2 

51  1 

64  2 

66  5 

68  ° 

1903 

3  77 

4  84 

6  30 

3  59 

4  1° 

4  26 

1904 

'N  5 

28  8 

42  2 

51  2 

64  7 

71  8 

1904 

1  85 

3  39 

1  93 

4  00 

1905  

30.5 

26.3 

45.4 

65.6 

66.4 

72.0 

1905  

3.93 

3.28 

2.76 

2.97 

3.97 

3.19 

Means  

32.1 

30.5 

44.9 

53.2 

64.9 

71.8 

Means  

3.14 

2/TO~ 

3.70 

3.84 

2.81 

3.71 

THE  HYDROGRAPHY  OF  CALVERT  COUNTY 


BY 

:  C.  GROVER 


Calvert  County,  situated  upon  the  southern  end  of  the  narrow  tongue 
of  land  between  the  Chesapeake  Bay  and  the  Patuxent  Eiver,  has  no  rivers 
of  commercial  importance  within  its  boundaries.  The  rainfall  is  well  dis- 
tributed and  there  is  consequently  no  irrigation,  hence  the  hydrography 
is  relatively  unimportant. 

The  tides  in  Chesapeake  Bay  within  the  limits  of  this  county  have  a 
mean  range  of  1.4  feet  at  Cove  Point  and  1  foot  at  the  northern 
extremity  of  the  county.  The  tides  in  the  Patuxent  Kiver  extend  beyond 
the  northern  limits  of  the  county,  and  the  mean  range  is  1.2  feet  at 
Drum  Point  near  the  southern  end  of  the  count}',  and  1.5  feet  at 
Nottingham  near  the  northern  end.  The  rainfall  at  Solomons,  near  the 
southern  end,  has  averaged  39.49  inches  for  12  years,  while  at  Jewell, 
which  is  just  north  of  Calvert,  in  Anne  Arundel  County,  it  has  averaged 
43.93  for  9  years. 

The  surface  of  the  country  is  rolling  and  of  sufficient  slope  to  give 
good  drainage.  The  highest  elevations  near  the  northern  end  of  the 
county  are  about  180  feet.  The  streams  are  all  necessarily  short,  the 
maximum  width  of  the  county  being  not  more  than  10  miles,  and 
although  the  slopes  of  the  streams  are  in  many  instances  good,  yet  because 
of  their  small  size,  very  little  water-power  is  used. 

HALL    CREEK. 

The  headwaters  of  this  stream  lie  in  Anne  Arundel  County,  thence 
they  flow  southwesterly  across  Calvert  County  into  the  Patuxent  River. 
The  total  drainage  area  is  20  square  miles.  The  basin  is  sandy  and  rolling 


208  THE    HYDROGRAPHY    OF    CALVERT    COUNTY 

and  is  generally  in  farm  lands.  One  water-power  development  on  a 
tributary  of  this  creek  has  been  reported  to  the  Census,  viz.,  at  Chaney- 
ville,  where  10  horse-power  are  used.  No  measurements  of  flow  have 
been  made. 

LYONS    CREEK. 

This  creek  rises  in  Anne  Arundel  County,  flows  westerly,  forming 
the  northern  boundary  of  Calvert  County  for  nearly  half  of  its  length 
and  empties  into  the  Patuxent  River,  draining  a  total  area  of  21  square 
miles.  Its  basin  is  very  similar  to  that  of  Hall  Creek,  which  lies  just 
to  the  south  of  it.  The  Census  has  no  report  of  water-power  utilized 
on  this  stream.  No  measurements  of  flow  have  been  made. 

ST.   LEONARD   CREEK. 

This  stream  lies  in  the  southern  part  of  the  county,  flows  southerly 
through  several  miles  of  tidal  estuary  and  empties  into  the  Patuxent  River. 
The  total  drainage  area  is  22  square  miles.  In  the  upper  part  of  its 
course  the  slopes  are  good  and  one  water-power  development  has  been 
reported  to  the  Census,  viz.,  at  St.  Leonard,  where  25  horse-power  are 
utilized.  No  measurements  of  flow  have  been  made. 

Other  streams  in  the  county  with  the  areas  of  their  basins  are  stated 
below : 

Stream.  Drainage  Area.  Locality. 

Fishing        "  11.7  sq.  mi.  Mouth. 

Chew  "  15.5        "  Head  of  the  Estuary. 

Cocktown     "  6.3        "  Mouth. 

Hunting       "  7.3        "  Mouth. 

Parker    Creek.  15.7        "  Crossing  at  the  Chesapeake  St. 

R.  R.  Bridge. 

Nearly  all  these  are  tidal  in  the  lower  portions  of  their  courses  with 
good  slopes  above  tide  water. 


THE  MAGNETIC  DECLINATION  IN  CALVERT 
COUNTY 

BY 

L.  A.  BAUER 


Magnetic  observations  for  the  purpose  of  determining  the  magnetic 
declination  of  the  needle,  or  the  "  variation  of  the  compass,"  have  been 
made  by  the  Maryland  Geological  Survey  and  the  United  States  Coast 
and  Geodetic  Survey  at  the  following  points  within  the  county. 

TABLE   I. 
MAGNETIC  DECLINATIONS  OBSEEVED  IN  CALVEBT  COUNTY. 


No. 
28 

Station. 

Lati- 
tude. 

Longitude 
W.of 
Gr'nwich. 

Date  of 
Observation 

Magnetic 
Declination  on 

Observer. 

Remarks. 

Date 
west 

Jan.  1, 

1900,  west 

Prince  Fred'ck 

O        1 

3832.4 

0       / 

76  34.9 

Oct.  19,  1896 

5  10.4 

520. 

L.  A.  Bauer 

1896Sta.,C.H. 

2SA 

" 

"     » 

"     " 

June  25,  1900 

5  24.3 

22.9 

J.  B.  Baylor 

Merid.L.,S.M. 

2SB 

"           " 

"     " 

..     .i 

"       " 

5  18.6 

517.2 

"          " 

"      L..N.M. 

All  values  refer  to  mean  of  day    (24   hours). 

Since  January  1,  1900,  the  value  of  the  magnetic  decimation  has 
increased  annually  by  about  three  minutes  (3'),  so  that  on  January  1, 
1907,  for  example,  the  north  end  of  a  compass  would  bear  at  the  south 
meridian  stone  at  Prince  Frederick,  about  5°  45'  W.,  on  the  average  for 
the  day. 

DESCRIPTION   OF   STATIONS. 

Prince  Frederick.— The  station  of  1896  was  superseded  by  the  1900 
stations,  which  are  as  follows:    28A  is  the  south  monument  of  the 
meridian  line  established  in  the  court-house  square  in  1900,  this  monu- 
ment being  13.8  feet  from  the  south  fence  and  33.3  feet  from  the  east 
15 


210  THE    MAGNETIC   DECLINATION   IN    CALVEET    COUNTY 

fence.     Station  28B  is  the  north  monument  of  this  meridian  line  and 
is  about  200  feet  north  of  the  south  stone. 

For  a  description  of  the  methods  and  instruments  used,  reference 
must  be  made  to  the  "  First  Eeport  upon  Magnetic  Work  in  Maryland," 
vol.  i,  Maryland  Geological  Survey  Eeport.  This  report  gives  likewise 
an  historical  account  of  the  phenomena  of  the  compass-needle  and 
discusses  fully  the  difficulties  encountered  by  the  surveyor  on  account 
of  the  many  fluctuations  to  which  the  compass-needle  is  subject.  In  the 
Second  Eeport  (Md.  Geol.  Survey,  vol.  v,  pt.  1,  1905),  the  various  values 
observed  in  Maryland  have  been  collected  and  reduced.  Surveyors  of  the 
county  desiring  these  reports,  should  address  the  State  Geologist. 

MERIDIAN    LINE. 

On  June  25,  1900,  Mr.  J.  B.  Baylor,  acting  under  instructions  of 
the  Superintendent  of  the  United  States  Coast  and  Geodetic  Survey 
as  issued  to  him,  in  response  to  a  request  from  the  State  Geologist 
established  a  true  meridian  line  at  Prince  Frederick  in  the  Court-house 
Square.  This  line  is  marked  by  two  substantial  monuments,  suitably 
lettered  and  firmly  planted  in  the  ground.  (See  description  above.) 

THE  STONE  WHICH  is  BEST  REMOVED  FROM  ALL  DISTURBING  INFLU- 
ENCES, SHOULD  BE  THE  ONE  TO  BE  USED  BY  SURVEYORS  WHEN  MAKING 
THEIR  TESTS. 

When  the  surveyor  determines  the  value  of  the  magnetic  declination, 
it  would  be  well  for  him  to  make  the  observations  on  several  days,  if 
possible.  Probably  the  best  time  of  day  for  making  the  observations 
would  be  towards  evening,  about  5  or  6  o'clock.1  At  this  time  the 
declination  reaches,  approximately,  its  mean  value  for  the  day  (see 
Table  II).  The  observations  on  any  one  day  should  extend  over  at  least 
one-half  of  an  hour,  preferably  an  hour,  and  the  readings  should  be  taken 
every  ten  minutes.  Before  each  reading  of  the  needle  it  would  be  well 

1Or  the  surveyor  may  make  his  observations  in  the  morning  and  early 
in  the  afternoon,  at  about  the  time  of  minimum  and  maximum  values  of  the 
magnetic  declination.  He  may  regard  the  mean  of  the  two  extreme  values 
as  corresponding  closely  to  the  mean  value  for  the  day  (24  hours). 


MARYLAND   GEOLOGICAL    SURVEY 


211 


to  tap  2  the  plate  lightly  with  the  finger  or  a  pencil  so  as  to  slightly 
disturb  the  needle  from  the  position  of  rest  it  may  have  assumed.  The 
accurate  time  should  be  noted  opposite  each  reading  and  a  note  entered 
in  the  record-book  as  to  the  date,  the  weather  and  the  kind  of  time 
the  observer's  watch  was  keeping.  It  is  very  essential  that  the  surveyor 
should  have  some  knowledge  as  to  the  error*  of  his  compass.  He  can 
determine  this  by  making  observations  as  stated  at  the  South  or  North 
Meridian  Stone,  whichever  is  best  suited.  He  should  reduce  the  value 
of  5°  20'  to  the  date  of  his  tests,  by  allowing  an  annual  increase  since 
January  1,  1900,  as  above  stated,  of  3',  and  the  difference  between  this 
value  and  his  own  will  be  his  compass  error. 

If  the  surveyor  has  an  instrument  which  admits  of  the  refinement 
to  take  into  account  the  change  in  the  magnetic  declination  during  the 
day,  he  may  use  the  following  table  to  correct  his  readings : 

To  reduce  an  observation  of  the  magnetic  declination  to  the  mean 
value  for  the  day  of  24  hours,  apply  the  quantities  given  in  the  table 
below  with  the  sign  as  affixed : 


Month. 

6 

A.M. 

7 

8 

9 

10 

11 

1 

1 

'2 

3 

4 

5 

6 

P.M. 

January  
February  
March  

-0. 

+0.6 
+1.2 
+2.5 
+3.0 
+2.9 
+3.1 
+2.9 
+1.8 
+0.5 
+0.5 
+0.2 

+0.2 
+0.7 
+2.0 
+3.1 

+3.8 
+4.4 
+4.6 
+4.9 
+2.8 
+1.6 
+1.2 
+0.3 

/ 
-0.2 
-0.8 
-1.2 
-1-2 
-0.9 
-1.2 
-1.3 
-0.6 
-0.3 
-0.4 
-0.2 
-0.3 

+0.2 
-0.4 
-0.5 
-0.2 
+0.1 
-0.2 
-0.3 
+0.3 
-0.1 
-0.4 
+0.2 
+0.1 

+1.0 
+1.5 
+3.0 
+3.4 
+3.9 
+4.4 
4-4.9 
+5.4 
+3.4 
+3.1 
+1.7 
+0.8 

+2.1 
+1.9 
+2.8 
+2.6 
+2.6 
+3.3 
+3.9 
+3.7 
+2.5 
+2.8 
+1.8 
+1.8 

+2.4 
+1.4 
+1.6 
+0.8 
+0.1 
+1.1 
+  1.8 
+0.4 
+0.3 
+1.4 
+1.1 
+1.8 

+1.2 

-!\ 

-5!o 

-1.2 

-2.1 
-1.0 
-0.5 
0.0 

-1.1 
-1.5 
-2.5 
-4.0 
-4.0 
-3.6 
-3.4 
-4.7 
-4.4 
-2.7 
-2.0 
-1.6 

-2.5 
-2.1 
-3.4 
-4.1 
-5.0 
-4.5 
-4.4 
-5.1 
-4.6 
-3.3 
—  2.7 
-2.4 

-2.6 
-2.5 
-3.7 
-4.2 
-4.5 
-4.5 
-4.7 
-4.9 
-4.2 
-3.4 
-2.6 
-2.3 

-2.1 
-2.0 
-3.3 
-3.6 
-3.6 
-3.8 
-4.2 
-3.7 
-4.0 
-2.4 
-1.8 
-1.8 

-1.3 
-1.2 
-2.3 
-2.3 
-2.3 
-2.6 
-2.8 
-1.9 
-1.4 
-1.3 
-1.0 
-1.1 

April 

May  

June  
July  

September... 
October  
November  
December  

This  table  shows  that  during  August,   for   example,  the   magnetic 

*  Great  care  must  be  taken  not  to  electrify  the  needle  by  rubbing  the  glass 
plate  in   any  manner.     Remarkable    deflections   of  the  needle  can  thus  be 
produced. 

*  I  have  found  surveyors'  compasses  to  differ  at  times  as  much  as  1°  from 
the  readings  with  the  Coast  and  Geodetic  Survey  Standard  Magnetometer. 
The  error  may  be  due  to  a  variety  of  causes,  such  as  an  imperfect  pivot, 
non-coincidence  of  magnetic  axis  of  needle  with  the  geometric  axis,  and  loss 
of  magnetism  of  the  needle. 


212 


THE   MAGNETIC   DECLINATION    IN    CALVERT   COUNTY 


declination  has  its  lowest  value  about  8  a.  m.  and  its  highest  value  at 
about  1  p.  m.,  and  that  between  these  two  hours  the  needle  changes  its 
direction  about  10',  which  amounts  to  15  feet  per  mile.  In  winter  the 
change  is  considerably  less. 

Table  III  shows  how  the  magnetic  declination  has  changed  at  Prince 
Frederick  between  1700  and  1905. 

TABLE    III. 


Year 

Needle 

Year 

Needle 

Year 

Needle 

Year 

Needle 

Jan.  1. 

pointed. 

Jan.  1. 

pointed. 

Jan.  1. 

pointed. 

Jan.  1. 

pointed. 

1700 

5°  31'  W 

1750 

2°  44'  W 

1800 

0°  49'  W 

18^0 

2°  22'  W 

10 

20 

I-B 

60 

70 

2   08 
1   36 

3 

0   49 
0   59 

60 
70 

3   00 
3   40 

30 

4   03 

80 

1   12 

80 

1   20 

80 

4   16 

40 

3   23 

90 

0   55 

40 

1   49 

90 

4   50 

60 

2   44   W 

1800 

0   49  W 

50 

2   22  W    i 

1900 

5   20 

19Q5 

5   35   W 

From  this  table  it  will  be  noticed  that  the  needle  is  at  the  present 
time  pointing  about  the  same  amount  to  the  west  that  it  did  two 
centuries  ago,  and  that  in  about  1805  the  magnetic  declination  had  its 
lowest  value  of  about  48'  west,  after  which  it  began  to  increase  again. 
In  about  a  century,  since  1805,  the  compass  has  accordingly  changed  its 
direction  by  about  4|°. 

A  street  a  mile  long,  laid  out  in  Prince  Frederick  in  1805  to  run  north 
and  south  by  the  compass,  would,  at  the  present  time,  have  its  north 
terminus  about  1/12  of  a  mile  too  far  east! 

The  above  table  enables  the  surveyor  to  ascertain  the  precise  amount 
of  change  of  the  magnetic  declination  or  pointing  of  the  compass 
for  any  two  dates  between  1700  and  1905.  It  should  be  emphasized 
however,  that  when  applying  the  quantities  thus  found  in  the  re-running 
of  old  lines,  the  surveyor  should  not  forget  that  the  table  cannot  attempt 
to  give  the  correction  to  be  allowed  on  account  of  the  error  of  the 
compass  used  in  the  original  survey. 


THE  FORESTS  OF  CALVERT  COUNTY 

BY 

H.  M.  CURRAN 


AREA  OF  COUNTY. 

The  total  area  of  Calvert  County  is  218  square  miles,  or  139,520 
acres.  This  includes  3420  acres  of  marsh.  The  total  land  area  is  there- 
fore 136,100  acres.  Thirty-seven  per  cent  of  this,  or  51,000  acres,  is 
timbered,  and  the  remaining  85,000  acres  is  either  in  cultivation  or  was 
formerly  and  has  been  recently  abandoned.  The  accompanying  map 
shows  the  distribution  of  wood  and  farm  lands.  Abandoned  fields  with 
a  growth  of  scrub  pine  are  not  included  in  the  timbered  areas. 

WOODLANDS. 

All  available  land  is  or  has  been  under  cultivation.  The  timber  is 
confined  to  the  not  readily  tillable  areas  along  the  streams.  These 
wooded  sides  of  the  stream  depressions  furnish  the  only  important  type 
of  timber  found  in  the  county.  The  name  "  slope  timber  "  is  given  to 
this  type.  It  resembles  very  closely  the  shore  timber  of  Cecil  County. 
The  timber  of  the  bottoms  is  not  uniform  in  composition,  and  its  small 
area  prevents  the  discussion  of  it  as  a  distinct  type.  Small  areas  were 
measured  to  show  the  composition  of  the  stands.  Old  field  growth  of 
loblolly  and  scrub  pines  were  also  measured  for  stand  tables. 

Slope  Timber. 

The  51,000  acres  of  timbered  land  in  the  county  are  practically  all 
included  within  the  slope  timber.  The  distribution  of  this  type  is  seen 
from  the  map  to  be  along  the  sides  of  depressions  occupied 


214  THE   FORESTS    OF    CALVEET   COUNTY 

by  creeks.  In  composition  the  type  varies  little  in  different  parts  of  the 
county.  The  greatest  variation  is  found  along  individual  streams. 
Chestnut,  oak,  and  hickory,  on  the  steep  upper  slopes  of  the  headwaters 
and  small  tributaries,  give  place  to  gum,  ash,  elm,  and  willow  in  the 
narrow  bottoms  and  on  gentle  slopes  near  the  Bay  and  river.  As  the 
area  of  the  bottoms  is  very  small  and  the  gentle  slopes  mostly  under 
cultivation,  the  slope  timber  may  be  considered  fairly  uniform  in 
composition. 

The  following  table  gives  in  detail  the  character  and  composition  of 
the  typical  stands: 


(Average  of  61 
Species. 

Chestnut 

TA 
acres  —  sound  tr< 

Average  number 
of  trees 
per  acre. 

31  95 

BLE  I. 

3es  5  inches  and  over  in  diameter.) 

Per  cent               Average                Average 
of  each               diameter                  stand 
species.             breasthigh.             per  acre. 
Inches.                  Cords. 
26.5                   16.6                     6.33 
12.0                    11.2                      1.08 
10.7                    15.4                      1.57 
10.3                    14.6                      1.17 
8.0                    10.9                      1.25 
5.6                    10.8                        .32 
3.8                    13.4                        .47 
3.8                    10.1                        .37 
3.0                    15.1                        .38 
.7                      9.5                        .60 
15.6                    10.2                      1.30 
100.0                     133                     14  84. 

Beech 

14  34 

White  Oak 

12  90 

Red  Oak 

12  48 

Red  Gum 

9  57 

Hickories 

6  80 

Chestnut  Oak 

469 

Scrub  Pine    . 

4  63 

Yellow  Poplar    .... 

3  76 

Ashes    

88 

Other  Species     .... 

18  72 

Total    . 

..    120.72 

Stream  Bottoms. 

Along  the  creeks  where  the  fall  is  slight,  narrow  bottom  lands  are 
sometimes  found.  The  growth  on  these  areas  is  entirely  different  from 
that  of  the  slopes.  It  varies  from  an  almost  pure  stand  of  willow  on 
the  bottoms  of  small  areas  to  stands  with  ash  predominating  or  pure 
stands  of  cypress.  The  following  tables  give  the  characters  of  two 
small  stands  of  bottom  timber,  the  one  with  ash  predominating,  the 
other  with  cypress.  The  latter  is  a  second  growth,  most  of  the  large 
trees  having  been  removed  very  recently. 


MARYLAND  GEOLOGICAL  SURVEY. 


CALVERT  COUNTY,   PLATE  XI. 


FlG.    I. — VIEW   SHOWING  CYPRESS   SWAMP,  BATTLE  CREEK. 


FlG.      2.— VIEW  SHOWING  SLOPE  TIMBER. 


MARYLAND   GEOLOGICAL    SURVEY  215 

TABLE  II. 

ASH  BOTTOMS. 

(Average  of  5  acres — sound  trees  5  inches  and  over  in  diameter.) 


Species. 
Ash 

Average  number 
of  trees 
per  acre. 

64  4 

Per  cent 
of  each 
species. 

46  53 

Average 
diameter 
breasthigh. 
Inches. 

Q    00 

Maximum 
diameter 
breasthigh. 
Inches. 

Elm 

12  0 

8  67 

Q  0?. 

00  n 

Sycamore     

17  0 

12  29 

12  80 

34  0 

Red  Maple     

13  4 

9  68 

10  70 

30  0 

Red  Gum  

11  4 

8  24 

7  gi 

14  0 

Willow    

15.2 

10  98 

10  40 

20  0 

Other  Species   .  .  . 

50 

3  61 

8  08 

20  0 

Total    

138.4 

100.00 

9.70 

25.4 

TABLE  III. 

CYPRESS  SWAMP. 

(Average  of  5  acres — sound  trees  5  inches  and  over  in  diameter.) 


Species. 
Cypress 

Average  number 
of  trees 
per  acre. 

177  4 

Per  cent 
of  each 
species. 

92.88 

Average 
diameter 
breasthigh. 
Inches. 

10.06 

Maximum 
diameter 
breasthigh. 
Inches. 

60 

Other  Species 

13.6 

7.12 

15.32 

36 

Total     . 

.   191.0 

100.00 

12.69 

48 

Old  Fields. 

Cultivated  areas  when  neglected  for  a  few  years  are  quickly  seeded  to 
pine.  In  the  northern  part  of  the  county  scrub  pine  is  the  common 
growth,  while  in  the  southern  end  the  loblolly  often  predominates. 
Scrub  pine  is,  however,  the  common  and  characteristic  growth  of  the 
old  fields.  These  are  found  in  all  parts  of  the  county  and  usually  on 
the  upper  slope  above  streams.  It  is  a  fairly  common  practice  to  allow 
fields  to  rest  in  this  way  for  a  number  of  years  when  they  are  again 
cleared  of  pine  and  cultivated.  For  this  reason  the  old  fields  have  been 
included  in  the  agricultural  areas.  The  following  tables  give  an  idea 
of  the  older  stand  on  these  once  cultivated  areas.  The  first  table  shows 
a  stand  of  scrub  pine,  the  second  one  of  loblolly  pine. 


216  THE   FORESTS   OF   CALVEET  COUNTY 

TABLE  IV. 

SCRUB  PINE. 

(Average  of  21  acres — sound  trees  5  inches  or  over  in  diameter.) 

Average  number  Per  cent  Average  Maximum 

Species.                           of  trees  of  each  diameter  diameter 

per  acre.  species.  breasthigh.  breasthigh. 

Inches.  Inches. 

Scrub  Pine    223.45  89.47  8.0  19.00 

Shortleaf  Pine     11.69  4.70  11.5  19.00 

Loblolly  Pine     6.18  2.47  9.0  18.00 

Other  Species   8.41  3.36  8.3  19.00 

Total    249.73  100.00  8.2  18.75 

TABLE  V. 

LOBLOLLY  PINE. 

(Average  of  7  acres — sound  trees  5  inches  and  over  in  diameter.) 

Average  Per  cent  Average  Maximum 

Species.                                of  trees  of  each  diameter  diameter 

per  acre.  species.  breasthigh.  breasthigh. 

Inches.  Inches. 

Loblolly    Pine    132.0                     62.69  9.08  28.0 

Scrub  Pine    52.1                     24.76  7.50  19.0 

Other  Species     26.4                     12.55  7.88  24.0 

Total    210.5  100.00  8.15  20.3 

Forest  Trees. 

There  are  51  species  of  forest  trees  occurring  within  the  county.  Of 
these  5  are  conifers  and  the  remainder  broad-leafed  or  hardwood  species. 
This  list  does  not  include  introduced  American  or  foreign  trees. 

CONIFEBS. 
Common  Name.  Botanical  Name. 

1.  Loblolly  Pine Pinus  taeda  Linne". 

2.  Scrub  Pine Pinus  virginiana  Mill. 

3.  Shortleaf  Pine Pinus  echinata  Mill. 

4.  Cypress    Taxodium  distichum  (Linne")  Rich. 

5.  Red  Cedar   Juniperus  virginiana  Linn6. 

HARDWOODS. 

6.  Black  Walnut Juglans  nigra  Linne". 

7.  Bitternut  Hickory  Hicoria  minima  (Marsh)  Britton. 

8.  Mockernut  Hickory  Hicoria  alba  (Marsh)  Britton. 

9.  Pignut  Hickory Hicoria  glabra  (Mill)  Britton. 

10.  Black  Willow Salix  nigra  Marsh. 

11.  River  Birch  Betula  nigra  Linne. 

12.  Blue  Beech  Carpinus  caroliniana  Walt. 


MARYLAND  GEOLOGICAL  SURVEY. 


CALVERT  COUNTY,  PLATE  XII. 


MARYLAND   GEOLOGICAL   SURVEY  217 

13.  Beech   Fagus  atropunicea  (Marsh)  Sudw. 

14.  Chinquapin     Costarica  pumila  (Linn6)  Mill. 

15.  Chestnut    Castanea  dentata  (Marsh)  Borkh. 

16.  White  Oak   Quercus  alba  Linn6. 

17.  Post  Oak  ; Quercus  minor  (Marsh)  Sargent. 

18.  Chestnut  Oak Quercus  prinus  Linne\ 

19.  Cow  Oak  Quercus  michauxii  Nutt. 

20.  Red  Oak   Quercus  rubra  Linng. 

21.  Scarlet  Oak   Quercus  coccinea  Muench. 

22.  Yellow  Oak Quercus  velutina  Lam. 

23.  Spanish  Oak   Quercus  digitata  (Marsh)  Sudw. 

24.  Pin  Oak Quercus  palustris  Muench. 

25.  Black  Jack  Quercus  marilandica  Muench. 

26.  Willow    Oak    Quercus  phellos  Linne". 

27.  Slippery   Elm    Ulmus  pubescens  Walt. 

28.  White  Elm  Ulmus  americana  Linne". 

29.  Hackberry Celtis  occidentalis  Linne\ 

30.  Red  Mulberry Morus  rubra  Linne". 

31.  Sweet  Magnolia Magnolia  glauca  Linne". 

32.  Yellow  Poplar  Liriodendron  tulipifera  Linne". 

33.  Papaw    Asimina  triloba  (Linn6)   Dunal. 

34.  Sassafras    Sassafras  sassafras  (Linne")  Karst. 

35.  Witch  Hazel Hamamelis  virginiana  Linne". 

36.  Red  Gum Liquidambar  styraciftua  Linn6. 

37.  Sycamore    Platanus  occidentalis  Linne". 

38.  Cockspur  Thorn  Crataegus  crus-galli  Linng. 

39.  Scarlet  Haw Crataegus  coccinea  Linne". 

40.  Black  Cherry Prunus  serotina  Ehrh. 

41.  Red  Bud  Cercis  canadensis  Linnet 

42.  Locust    Robinia  pseudacacia  Linne. 

43.  Staghorn  Sumach    Rhus  hirta  (Linne")  Sudw. 

44.  American  Holly  Ilex  opaca  Ait. 

45.  Red  Maple   Acer  rubrum  Linne". 

46.  Flowering  Dogwood    Cornus  florida  Linne\ 

47.  Black  Gum  Nyssa  sylvatica  Marsh. 

48.  Mountain  Laurel   Kalmia  latifolia  Linne". 

49.  Persimmon  Diospyros  virginiana  Linn6. 

50.  White  Ash   Fraxinus  americana  Linn6. 

51.  Red  Ash  Fraxinus  pennsylvanica  Marsh. 

52.  Nannyberry    Viburnum  prunifolium  Linn6. 

The  principal  commercial  trees  of  the  county  are  the  oaks,  pines,  hick- 
ories, ashes,  chestnut,  yellow  poplar,  and  cypress.  The  white  and  Spanish 
oaks,  scrub  and  loblolly  pines,  hickory,  and  chestnut  predominate  and 
occupy  the  upper  slopes,  while  the  ash,  yellow  poplar,  and  cypress  are 


218  THE    FORESTS    OF    CALVEET   COUNTY 

found  along  the  streams.     Among  the  trees  of  little  commercial  import- 
ance the  red  gum  and  beech  occur  in  the  greatest  numbers. 

Wood  Consumption. 

Wood  is  cut,  manufactured,  and  used  in  the  county  for  a  variety  of 
purposes.  With  the  exception  of  a  small  amount  of  ship  timber  the 
entire  wood  output  is  consumed  locally.  Fuel,  fencing,  lumber,  shingles, 
ship  timber,  piling,  ties,  and  telegraph  poles  are  the  principal  forms  in 
which  the  wood  is  used.  Of  these  the  amount  used  as  fuel,  fencing,  and 
rough  timber  for  local  consumption  is  greatly  in  excess  of  all  other 
material.  The  timber  industries  of  the  county  are  poorly  developed,  the 
few  portable  mills  poorly  equipped  and  the  manufactured  material  of 
low  grade. 

The  bulk  of  the  timber  cut  to  furnish  the  above  material  is  from  four 
kinds  of  wood :  pine,  oak,  chestnut,  and  cypress. 

Pine  is  used  as  fuel,  lumber,  and  piling;  oak  as  fuel,  fencing,  lumber, 
ship  timber,  and  ties;  chestnut  as  fencing,  lumber,  shingles,  ties,  and 
telegraph  poles;  cypress  as  lumber  and  shingles. 

Materials  for  fuel  and  fencing  in  excess  of  local  demand  will  probably 
always  be  present  in  the  county.  Special  materials  are  available  in 
small  quantities  only,  and  a  very  limited  and  constantly  decreasing 
annual  cut  can  be  made.  This  is  due  to  the  practice  of  using  the  best 
material  for  all  purposes  when  inferior  material  would  do  as  well  for 
some  of  them.  This  practice,  so  common  in  all  purely  farming  regions, 
results  in  stands  of  inferior  trees  and  species  suitable  only  for  cord- 
wood. 

PAST  TREATMENT  OF  WOODLANDS. 

While  the  timbered  areas  of  the  county  have  increased  rather  than 
decreased  in  the  past  thirty  years,  the  kind  and  quality  of  the  timber 
produced  has  materially  changed.  Areas  that  once  yielded  good  white 
oak,  chestnut,  yellow  poplar,  hickory,  walnut,  cherry,  ash,  and  cypress 
now  produce  little  or  none  of  these  materials.  This  good  material  has 
disappeared  and  in  most  instances  yielded  no  revenue  to  the  owners, 


MARYLAND  GEOLOGICAL  SURVEY, 


CALVERT  COUNTY,  PLATE  XIII. 


FlG.    I.— VIEW    SHOWING    SCRUB  PINE   SEEDING  ERODED   SLOPES. 


FlG.   2. — VIEW   SHOWING   SCRUB   PINE  SEEDING  ERODED   SLOPES. 


MARYLAND   GEOLOGICAL    SURVEY  219 

as  it  was  largely  used  to  furnish  fuel,  fencing,  and  local  construction 
timber.  No  provision  was  made  for  the  reproduction  of  a  desirable 
crop,  inferior  species  were  left  to  occupy  the  ground,  and  as  a  result 
there  remain  defective  old  trees  of  the  desirable  species  and  a  large 
amount  of  undesirable  trees  like  gum,  willow,  sassafras,  sycamore,  and 
scrub  pine.  Such  trees  as  the  chestnut  and  yellow  poplar  being  vigorous 
sprouters,  have  in  many  places  withstood  the  encroaching  of  inferior 
trees. 

Owing  to  the  fact  that  fires  are  not  prevalent  in  the  county  the  forest 
soils  have  remained  unchanged  and  their  capacity  for  timber  production 
is  normal.  They  are  capable  of  supporting  a  very  vigorous  growth  of 
all  desirable  species.  That  no  effort  is  being  made  to  grow  a  good  timber 
crop  is  partly  due  to  lack  of  interest  on  the  part  of  owners  and  tenants  on 
these  lands,  but  mainly  to  a  lack  of  knowledge  of  the  possibilities  of  the 
lands  for  timber  production  under  management. 

FUTURE  IMPROVEMENT. 

The  forest  lands  of  the  county  are  in  a  depleted  condition,  yielding  but 
15  cords  of  wood  per  acre  where  they  should  yield  15,000  feet  of  good 
lumber.  There  are  in  the  county  50,000  acres  capable  of  producing 
good  grades  of  chestnut,  white  oak,  and  yellow  poplar.  These  lands  are 
capable  of  a  minimum  yield  of  15,000  feet  per  acre.  This  means  a  gross 
yield  for  the  county  of  750,000,000  feet  of  lumber  worth,  at  present 
prices  of  the  lower  grades,  $7,500,000.  This  crop  is  easily  started  (in 
many  places  is  already  started),  and  requires  but  little  attention,  and 
that  at  a  time  when  other  work  on  the  farm  is  not  pressing;  the  harvest 
is  certain  and  the  product  readily  sold.  The  arguments  so  often  advanced 
against  the  holding  of  timber  do  not  apply  to  the  lands  in  this  county. 
The  timbered  areas  are  portions  of  small  farm  holdings  that  have  been 
in  the  hands  of  the  present  owners  or  their  families  from  one  to  five 
generations,  and  taxes  are  paid  annually  on  these  lands  whether  they 
yield  a  revenue  or  not.  There  is  nothing  to  prevent  the  growing  of  a 
timber  crop  but  the  lack  of  interest  and  information  on  the  part  of  the 
owners  of  forest  lands. 


220  THE   FORESTS   OF   CALVEET  COUNTY 

The  fact  that  it  takes  from  fifty  to  one  hundred  years  to  mature  timber 
is  no  drawback  to  the  starting  and  tending  of  such  a  crop.  With  proper 
care  the  timber  lands  will  annually  furnish  the  necessary  fuel  and  fencing 
and  each  year  see  an  improvement  of  the  stand  as  a  result  of  this  care. 
The  present  treatment  is  reducing  the  forest  to  the  production  of  nothing 
but  cordwood.  A  proper  treatment  will  provide  a  plentiful  supply  of 
cordwood  and  also  a  good  marketable  stand  of  lumber-producing  trees. 
Property  thus  treated  increases  in  value  and  is  an  excellent  investment. 

That  the  desirable  species  can  be  grown  to  merchantable  sizes  is  shown 
by  Table  I.  On  62  acres  of  slope  timber  measured  in  different  parts  of 
the  county,  40  per  cent  of  the  stand  was  chestnut,  white  oak,  and  yellow 
poplar.  The  trees  ranged  in  diameter  from  5  to  10  inches. 

The  following  tables  show  the  number  of  trees  of  different  diameter 
required  to  produce  the  stand  of  15,000  feet  of  lumber  per  acre : 

TABLE  VI. 
(Average  number  of  trees  to  produce  1000  feet  of  lumber.) 

Species.  Diameter  breasthigrh. 

18  inches.       24  inches       30  inches. 

Chestnut   4  2  1 

White  Oak    5  2  1 

Yellow  Poplar  4  2  1 

TABLE  VII. 
(Number  of  trees  to  produce  stand  of  15,000  feet  of  lumber.) 

Chestnut    50  per  cent  =  7.5  M 

White  Oak 40     "     "     =  6.0  M 

Yellow  Poplar 10     "     "     =  1.5  M 

Diameter  breasthigh. 
18  inches.          24  inches.  30  inches. 

Chestnut   30  15  8 

White  Oak   30  12  6 

Yellow  Poplar  6  3  2 

Total 66  30  16 

It  is  necessary  to  have  from  16  to  66  trees  per  acre  of  chestnut,  white 
oak,  and  yellow  poplar  to  produce  the  desired  stand. 

On  the  62  acres  of  slope  timber  measured  there  were  48  trees  per  acre 
of  this  species,  and  if  we  include  the  red  and  chestnut  oaks,  we  have  65 


MARYLAND  GEOLOGICAL  SURVEV. 


CALVERT  COUNTY,  PLATE  XIV. 


FlG.    I. — VIEW   SHOWING  THE  DEVELOPMENT  OF  THE  WHITE  OAK   AS   A   SHADE  TREE. 


FlG.   2. — VIEW   SHOWING    SCRUB   PINE   FOR   CORDWOOD. 


MARYLAND   GEOLOGICAL    SURVEY  221 

trees  per  acre.  In  other  words,  the  desired  species  are  present  in  number 
almost  sufficient  for  the  estimated  stand  and  by  the  substitution  of 
species  of  slightly  inferior  character  we  have  the  desired  number. 

From  the  foregoing  it  is  seen  that  the  crop  desired  can  be  grown  and 
that  the  crop  is  already  started.  The  problem  is,  therefore,  a  simple 
one  of  proper  treatment.  The  following  suggestions  as  to  the  care  of 
the  crop  will,  if  followed,  do  much  to  bring  the  forests  of  the  county  into 
good  growing  condition.1 

CULTURAL  TREATMENT. 

The  principal  part  of  the  crop  is  to  come  from  chestnut,  white  oak, 
and  yellow  poplar.  It  is,  therefore,  first  necessary  to  take  account  of 
stock  and  find  out  what  species  are  present  and  in  what  number  and 
size.  If  we  find  the  desirable  trees  are  absent  steps  must  be  taken  to 
establish  them,  either  by  natural  seeding  or  planting.  On  the  greater 
part  of  the  timbered  areas  of  the  county,  chestnut,  white  oak,  and  yellow 
poplar  are  present,  so  that  seeding  and  planting  will  be  necessary  only  on 
small  areas. 

The  first  step  in  the  care  of  the  crop  is  one  that  corresponds  to  thin- 
ning or  weeding.  Old  or  defective  oak,  chestnut,  or  yellow  poplar  which 
are  crowding  young  growth,  or  occupying  good  ground  that  might  pro- 
duce young  trees  are  to  be  removed.  Defective,  crooked,  or  stunted  young 
oaks,  chestnut,  and  yellow  poplar  are  also  to  be  removed,  and  with  them 
such  inferior  trees  as  gum,  maple,  beech,  sassafras,  and  sycamore. 

This  thinning  or  weeding  is  to  take  place  gradually  and  only  as  fast 
as  the  materials  removed  can  be  used.  They  are  to  furnish  the  fuel, 
fencing,  and  construction  timber  used  annually.  These  cuttings  should 
be  so  regulated  that  the  oak,  chestnut,  and  yellow  poplar  shall  seed  in 
the  openings  made.  In  removing  inferior  species,  especially  those  which 
sprout  readily,  care  should  be  taken  to  prevent  their  coming  in  again  on 
the  cleared  area.  Openings  should  never  be  large,  as  the  admission  of 

1More  detailed  information  and  assistance  may  be  had  by  applying  to  the 
State  Forester,  Baltimore,  Md. 


222  THE   FORESTS    OF    CALVERT   COUNTY 

light  may,  by  drying  or  in  less  direct  ways,  injure  the  productivity  of 
the  soil. 

Small  areas  which  are  unfit  for  growing  the  main  species  of  the  crop 
may  be  allowed  to  produce  the  natural  growth  if  valuable  or  of  only 
moderate  commercial  value.  This  especially  applies  to  the  ash  and 
cypress  lands  and  denuded  areas  in  pine. 

After  the  crop  has  been  started  and  the  undesirable  trees  removed,  a 
thinning  should  be  made  of  the  young  stands  which  have  too  many  trees 
per  acre  for  their  best  development.  This  thinning  should  take  place 
only  after  the  trees  have  grown  20  to  50  feet  in  height  and  dropped  their 
lower  limbs.  Several  thinnings  of  this  kind  may  be  necessary  before  the 
tree  reaches  maturity.  The  rule  that  thinning  shall  take  place  as  fast 
as  material  can  be  removed  and  utilized,  applies  to  all  cuttings.  The 
object  of  this  thinning  of  dense  stands  is  to  allow  the  young  trees  to  make 
as  rapid  a  diameter  growth  as  possible,  thus  .bringing  them  to  merchant- 
able sizes  early.  After  trees  have  reached  merchantable  sizes  they  may 
be  cut  and  sold  at  such  time  and  in  such  quantity  as  best  serves  the 
owner's  interests.  This  cutting  of  the  mature  crop  should  also  be  so 
regulated  that  reproduction  either  by  seeds  or  sprouts  may  take  place  and 
a  second  crop  replace  the  one  harvested. 

No  area  of  the  county  capable  of  producing  timber  and  unfit  for  agri- 
culture should  be  allowed  to  remain  without  a  good  timber  crop.  Such 
areas  are  not  only  idle  capital  but  self  destructive  through  taxes.  A 
policy  which  aims  at  the  proper  care  and  utilization  of  the  forest  re- 
sources of  the  county  will  add  materially  to  its  prosperity. 


INDEX 


Abbe,  Cleveland,  Jr.,  49. 

Advent  of  Spring  at  Solomons,   197. 

Agricultural    conditions,    discussed,    161. 

Alexander,  John  H.,  30,  41. 

Alexander  map,  30. 

Alsop  map,  27. 

Analyses  of  Leonardtown  Loam,  147. 

of  Norfolk  Loam,  143. 

of  Norfolk  Sand,  154. 

of  Sassafras  Loam,  156. 

of  Sassafras  Sandy  Loam,  158. 

of  Windsor  Sand,  151. 
Areal  distribution  of  Calvert  formation, 
70. 

of  Choptank  formation,  79. 

of  St.  Mary's  formation,  83. 

of  Sunderland  formation,  94. 

of  Talbot  formation,  102. 

of  Wicomico  formation,  99. 
Areas  of  soils,  141. 
Artesian  wells,  133. 
Ash  bottoms,  215. 
Atkinson,  Gordon  T.,  5. 

B 

Bagg,  R.   M.,  Jr.,  51. 

Bailey,  J.  W.,  43. 

Battle  Creek,  60,  111. 

Bauer,  L.  A.,   18,  48,  50,  209. 

Baylor,  J.  B.,  210. 

Ben  Creek,  71,  75. 

Berry,  E.  W.,  7. 

Bibbins,  A.,  7,  113. 

Bodkin  Point,   112. 

Bonsteel,  Jay  A.,  17,  38,  50,  135. 

Bowens,  128. 

Boyer,  C.  S.,  51. 

Buena  Vista,  section  near,  104. 

Building-stone,    128. 

Burke,  R.  T.  Avon,  17,  38,  50,  135. 


Calvert  Cliffs,  26,  31,  58,  70,  71,  72,  75, 

76,  78,  79,  80,  81,  82,  85,  86. 
Calvert    County,    agricultural    conditions 

in,  161. 

artesian  wells  in,  133. 
building-stone  of,  128. 
clays  of,  123. 


climate  of,  169. 

diatomaceous  earth  of,  130. 

drainage  of,  59. 

dug  wells  in,  132. 

economic  resources  of,  123. 

Eocene  in,  68. 

forest  trees  of,  216. 

geology  of,  67. 

gravels  of,  128. 

hydrography  of,   207. 

magnetic  declination  In,  209. 

marls  of,  128. 

meteorological    data    available    for, 
177. 

Miocene  in,  70. 

natural  deposits  in,  123. 

physical  features  of,  21. 

physiography   of,    55. 

Pleistocene  In,  93. 

precipitation  in,  181. 

sands  of,  127. 

soils  of,  135. 

soil   types   in,   141. 

springs   in,    132. 

structure  of  coastal  plain    in,  61. 

temperature  conditions  in,  178. 

topographic  description  of,  56. 

transportation  facilities  in,  22. 

water  resources  of,  131. 

wood  consumption  in,  218. 
Calvert  formation,   70. 

areal   distribution  of,   70. 

character  of  materials  of,  73. 

stratigraphic  relations  of,  73. 

strike,  dip  and  thickness  of,  72. 

sub-divisions    of,    73. 
Calvert  water  horizon,  134. 
Case,  E.  C.,  51. 
Chancellor  Point,  85. 
Chaney,  73. 

Character   of  materials   of   Calvert   for- 
mation, 73. 

of  Choptank  formation,  80. 
of  St.   Mary's  formation,  84. 
of  Sunderland  formation,  96. 
of  Talbot  formation,  103. 
of  Wicomico   formation,    100. 
Chesapeake  Beach,  58,  70,  71,  75,  76,  77, 

78,  99,  102,  120. 
artesian  well  at,  133. 
section  at,  87. 


224 


INDEX 


Chesapeake  Group,  70. 

sedimentary  record  of,   106. 
Chew  Creek,  drainage  area  of,  208. 
Choptank  formation,  78. 

areal  distribution  of,  79. 

character  of  materials  of,  80. 

stratigraphlc  relations  of,   81. 

strike,  dip  and  thickness  of,  80. 

sub-divisions  of,  81. 
Clark,  Wm.  Bullock,  7,  46,  47,  48,  49,  50, 

51,  52. 

Clays,  discussed,  123. 
Climate,  discussed,  169. 
Climatology  of  Solomons,  182. 
Coastal  plain  in  Maryland,  56. 
Cocktown  Creek,  60,  79. 

drainage  area  of,  208. 
Columbia  Group,  93. 

sedimentary  record  of,   107. 
Conifers,  discussed,  216. 
Conrad,  T.  A.,  33,  34,  40,  41,  42,  43,  44. 
Contents,    11. 
Cornfield  Harbor,  114. 
Cove  Point,  58,  59,  85,  95,  99,  102. 

section  near,  98. 

tides  at,  207. 

Cultural  treatment  of  forests,  221. 
Curran,  H.  M.,  18,  213. 
Cypress  swamps,   215. 


Fairhaven  dlatomaceous  earth,  73. 

Farrar  map,  27. 

Fassig,  Oliver  L.,  169,  176,  195. 

Ferry  Landing,  128. 

Finch,    John,   32,   40. 

Fisher,  R.   S.,  43. 

Fish  House,  121. 

Fishing  Creek,  60,  64,  79. 

drainage   area   of,    208. 
Flag   Pond,    30,   71,    72,   81,   82,    83,    85, 

95,    99. 

section  at,  91. 
section  near,  98. 
Forests,  discussed,  213. 
Forest  trees,  216. 

Fossils  from  Southern  Maryland,  33,  34. 
Fossils  of  the  Calvert  formation,  74,  75, 

76,  77,  78. 
of  the  Choptank  formation,  81,  82, 

83. 

of  the  St.  Mary's  formation,  85,  86. 
of  the  Sunderland  formation,  94,  96. 
of  the  Talbot  formation,  94,  103, 

113,  114. 
Frequency  and  duration  of  cold  periods 

at  Solomons,  195. 

Future    improvement    of    forest    lands, 
219. 


Dall,  W.  H.,  37,  46,  47,  48. 

Dana,  J.  D.,  35,  45. 

Dares  Wharf,  58,  71,  99,  102. 

sections  near,  89,  101,  105. 
Darton,  N.  H.,  36,  46,  47,  48. 
Day,  D.  T.,  45,  46,  47. 
Diatomaceous  earth,  discussed,  130. 
Drainage,    59. 
Drum  Cliff,  80,  82. 

Drum  Point,  22,  30,   59,   60,  70,  83,  85, 
86,  94,  95,  102,   103,   111,   207. 

section  near,  105. 
Ducatel,  J.  T.,  30,  41,  42. 
Dug  wells,   discussed,   132. 
Duration  of  dry  and  wet  periods  at  Solo- 
mons, 201. 


Eastman,  C.  R.,  51. 
Economic  resources,  discussed,  123. 
Eocene,  37,  68. 

Extremes   of   temperature   at    Solomons, 
191. 


Factors  controlling  climate,  169. 
Fairhaven,   74,   75. 
section  near,  86. 


Geographic  research  in  Calvert  County, 

26. 

Geologic  research  In  Calvert  County,  31. 
Geology,   discussed,    67. 
Geology  in  relation  to  soils,  137. 
Gibbes,  R.  W.,  43. 
Glenn,  L.  C.,  52. 
Governor  Run,  71,  72,  75,  80,  81. 

artesian  well  at,  134. 

sections  near,   91. 
Gravels,  discussed,  128. 
Griffith,  Dennis,  29. 
Grover,  N.  C.,  18,  207. 

H 

Hall  Creek,  60,  64,  71,  207. 

drainage  area  of,  207. 

section  near,  104. 
Hardwoods  of  Calvert  County,  216. 
Harlan,   R.,   42. 
Harris,    G.    D.,    47. 
Hay,  O.  P.,  52. 
Hayden,  H.  H.,  32,   40. 
Heilprin,    Angelo,    35,    36,    45. 
Hellen  Creek,  59,  60,  79. 
Hellen  Gut,  section  near,  104. 
Herrman,  Augustin,  28. 
Herrman  map,   28. 
Herrmann,  C.  F.  von,  17,   169. 


INDEX 


225 


Higgins,    James,    43,    45. 
Historical   review,   25. 
Rollick,   Arthur,   52. 
Hollin   Cliff,   30,   58. 

section  at,   101. 
Hoxton  map,   29. 
Hunting   Creek,    60,   64,    79. 

drainage    area    of,    208. 
Hydrography,  discussed,  207. 

I 

Illustrations,  list  of,  15. 

Influence  of  water  on  temperature,  173. 

Infusorial  earth,  130. 

Interpretation  of  Geologic  record,  106. 

Introduction,  21. 

Island  Creek,   60. 


Johnson,  A.  N.,  49. 


Leonardtown  Loam,  143. 

mechanical  analyses  of,  147. 
Lindenkohl,  A.,  46. 
Little  Cove  Point,  60,  96. 

section   at,    92. 
Loblolly  pine,  216. 
Local  sections,  discussed,  208. 
Local  sections  of  Miocene  age,  86. 

of  Sunderland  age,   98. 

of  Talbot  age,  104. 

of  Wicomico  age,  101. 
Lord  Baltimore  map,  27. 
Lower  Marlboro,   75. 
Lucas,  F.  A.,  52. 
Lyell,   Sir  Charles,  35,  43. 
Lyons  Creek,  60,  64,  71,  72,  74,  75,  94, 
95,    131. 

sections  near,   69,  86. 
Lyons  Creek  Wharf,  58,  69. 

M 

Mackall,    128. 

Maclure,  William,  32,  39,  40. 
Magnetic  declination,  discussed,  209. 
Magothy    water   horizon,    133. 
Markoe,   Francis,   Jr.,  42. 
Marls,  discussed,  128. 
Marriott   Hill,    62. 
Marsh,   William    Henry,    178,    182,    183, 

184,  197. 

Martin,  G.  C.,  52. 
Martinet  map,  30. 
Maryland  Geological  Survey,  31,  38,  48, 

49,  50,  51. 

Maryland  Silicate  Co.,  131. 
Mathews,  Edward  B.,  7,  49. 
16 


McGee,  W  J,  38,  46. 

Meadow  Land,  discussed,  158. 

Means   of   Max.    and   Min.    Temperature 

at  Solomons,  191. 
Meek,  F.  B.,  44. 
Meridian  Line,  210. 

instructions  for  using,  210. 
Merrill,   George   P.,    49. 
Meteorological    data    available    for    Cal- 

vert  County,  177. 
Mill  Creek,  60. 
Miller,  B.  L.,  7,  17,  53,  123. 
Millstone,  artesian  well  at,  134. 
Miocene,    70. 

local  sections  of,  86. 

origin  of  materials  of,  92. 
Morton,  S.  G.,  33,  34,  40. 
Mosquito  Point,  121. 

Mount    Harmony,    58,    59,    79,    81,    95, 
141. 

N 

Nanjemoy  formation,  68. 

sedimentary    record    of,    106. 
Natural    deposits    123. 
Newton,  R.  Bullen,  51. 
Nomlni   Cliffs,    72,   80. 
Norfolk    Loam,    141. 

mechanical  analyses  of,  143. 
Norfolk  Sand,  151. 

mechanical  analyses  of,  154. 
Nuttall,  Thomas,  32. 


Old   Fields,    215. 

Origin  of  Miocene   materials,   92. 

Origin   of   Pleistocene   materials,   105. 


Pamunkey  Group,  68.  ^ 

Parker   Creek,    60,    78,    79,    80,    81,    82, 

110. 

drainage  area  of,  208. 
sections  near,  90. 

Past  treatment  of  woodlands,  218. 
Patterson,    H.    J.,    130. 
Patuxent  river,   58,   59,   60,   61,  63,  64, 

65,   73,   75,   82,  84,   85,   94,  95, 

96,   99. 

Pearson,  artesian  well  at,  134. 
Physical  features,  discussed,   21. 
Physical  geography  in  relation  to  soils, 

135. 
Physiographic    features    in    relation    to 

climate,   171. 

Physiography,   discussed,    55. 
Pleistocene,  93. 

origin  of  materials  of,   105. 
Pliocene,  84. 


226 


INDEX 


Plum  Point,   75,    77,  99. 

sections  near,  88,  89. 
Plum  Point  Marls,  75. 
Point  of  Rocks,   58,    59,    71,   79,  80,    83, 

96,    102. 

Point  Patience,  157. 
Port  Republic,  59,  141. 
Precipitation,  discussed,   181. 
Precipitation,  at  Solomons,   198. 
Presson,  Alfred,   177. 
Prince  Frederick,    21,   59,   84,   135,   141, 
209,   210,   212. 

magnetic  station  at,  209. 

temperature    and    precipitation    at, 

206. 


Quaternary  clays,  discussed,  125. 


Recent  stage,  65. 
Remsen,   Ira,  5. 
Ries,  Heinrich,  51. 
Rogers,    W.   B.,   34,   41,   43. 
Rousby,  artesian  well  at,  134. 
manufacture  of  brick  at,  126. 


St.   Leonard  Creek,   60,   71,   79,   82,    95, 
99,   208. 

drainage  area  of,  208. 

section   near,    92. 
St.  Mary's  City,  83. 
St.  Mary's  formation,  83. 

areal  distribution  of,  83. 

character  of  materials  of,  84. 

stratlgraphic  relations  of,   84. 

strike,  .dip  and  thickness  of,  84. 

sub-divisions  of,   85. 
Sands,   discussed,  127. 
Sassafras    Loam,    154. 

mechanical  analyses  of,  156. 
Sassafras   Sandy   Loam,   157. 

mechanical    analyses   of,    158. 
Say,   Thomas,   40. 
Scharf,   J.  Thomas,  47. 
Scott,  Joseph,  39. 
Scrub  pine,   216. 
Sedimentary       record      of      Chesapeake 

Group,   106. 
Sedimentary  record  of  Columbia  Group, 

107. 

Sedimentary    record    of    Nanjemoy    for- 
mation, 106. 
Sellards,  E.   H.,  53. 
Shaler,    N.    S.,    45. 


Shattuck,    George   B.,    7,    17,   49,   50,    52, 

53,  67. 

Silvester,  R.  W.,  5. 
Sioussat,  St.  George  L.,  50. 
Slope   timber,    213. 
Smith,    Anthony,    29. 
Smith,  John,  26,  39. 
Smith  map,   26. 
Snowfall  at  Solomons,   203. 
Soils,   discussed,   135. 
Soil  types,  141. 
Solomons,   21,   135,   207. 

advent  of  Spring  at,  197. 

artesian  well  at,  134. 

climatology  of,   182. 

duration  of  dry  and  wet  periods  at, 
201. 

extremes  of  temperature  at,  191. 

frequency     and     duration     of     cold 
periods   at,    195. 

means    of   maximum    and    minimum 
temperature  at,  191. 

precipitation  at,  198. 

snowfall   at,  203. 

temperature  conditions  at,   183. 

warm    periods   at,    192. 

winds  and  weather  at,  204. 
Sotterly,  artesian  well  at,  134. 
Springs,   132. 

Stratigraphic    relations    of    Calvert    for- 
mation, 73. 

of  Choptank  formation,  81. 

of  St.  Mary's  formation,  84. 

of  Sunderland  formation,  96. 

of  Talbot  formation,   103. 

of  Wicomico  formation,  "101. 
Stream  bottoms,  214. 
Strike,    dip,    and    thickness    of    Calvert 
formation,  72. 

of  Choptank  formation,  79. 

of  St.  Mary's  formation,  84. 
Structure  of  coastal  plain,  61. 
Structure   and   thickness    of   Sunderland 
formation,  95. 

of  Talbot  formation,  102. 

of   Wicomico   formation,    100. 
Sub-divisions    of    Calvert    formation,    73. 

of  Choptank   formation,    81. 

of  St.   Mary's  formation,    85. 
Sunderland  formation,  94. 

areal  distribution  of,  94. 

character  of  materials  of,  96. 

local  sections  of,  98. 

stratigraphic  relations  of,  96. 

structure  and  thickness  of,  95. 
Sunderland  stage,  62. 
Susquehanna  Gravel,  147. 
Swamp  land,  160. 
Swartz,  C.  K.,  7. 


INDEX 


227 


Talbot  formation,    101. 

areal  distribution  of,  10?. 

character  of  materials  of,  103. 

local    sections   of,    104. 

stratigraphic  relations  of,   103. 

structure  and  thickness  of,   102. 
Talbot   stage,    64. 
Temperature     conditions    at     Salomons, 

183. 
Temperature      conditions      in      Calvert 

County,  178. 

Tertiary  clays,  discussed,  124. 
The    Willows,    59. 
Topographic  history,   53. 
Topographic    description,    56. 
Transmittal,  Letter  of,  9. 
Transportation  facilities,  22. 
Tripoli,  130. 
True,  Frederick  W.,  53. 
Tyson,  P.  T.,  44. 


Uhler,  P.  R.,  46. 

U.  S.  Bureau  of  Soils,  17. 

U.  S.  Coast  and  Geodetic  Survey,  30. 

U.   S.   Department  of  Agriculture,   18. 

U.  S.  Forest  Service,  18. 

U.  S.  Geological  Survey,  18. 

U.  S.  Weather  Bureau,  18. 

Ulrich,  E.  O.,  52,  53. 


Van  Renssellaer,  J.,  33,  40. 
Vanuxem,  L.,  40. 
Variation  of  the  compass,  209. 
Vaughan,  T.  W.,  52. 

W 

Walz,  F.  J.,   169,   197. 
Warfleld,  Edwin,  5,  9. 
Warm  periods  at  Solomons,   192. 
Water  resources,  discussed,   131. 
Whitney,    Milton,    47. 
Wicomico  formation,  99. 

areal  distribution  of,  99. 

character  of  materials  of,  100. 

local  sections  of,  1Q1. 

stratigraphic  relations  of,  101. 

structure  and  thickness  of,  100. 
Wicomico    stage,    63. 
Williams,   A.,   Jr.,   45. 
Williams,  G.  H.,  47,  48. 
Winds   and    weather   at    Solomons,    204. 
Windsor  Sand,   148. 

mechanical  analyses  of,   151. 
Wood  consumption,   218. 
Woodlands  of  Calvert  County,  213. 
Woolman,  Lewis,   47. 


Zones  of  the  Calvert  formation,  74,  75, 

76,  77,  78. 
of  the  Choptank  formation,  81,  82, 

83. 
of  the  St.  Mary's  formation,  85,  86. 


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